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Archive for the ‘Commodore CBM/PET family’ Category

Commodore CBM 4008

April 5th, 2016 No comments
Commodore CBM 4008

The Commodore PET 4000 series features Basic 4.0 as a standard feature, along with more memory and a lower price that made them attractive to schools.

Elementary, Middle, and High Schools all over Canada and the United States were filled with these impressive lumbering beasts. Introducing children far and wide to the wonders of BASIC programming. Another lesson taught was the importance of patience, since many schools provided only a tape datasette for loading and saving work.

Like the other models of PET, the 4000 series includes dual datasette ports, though only one is exposed to the outside of the casing. A standard IEEE-488 interface in the back allows the PET to connect to the numerous (and heavy) disk drives and printers being produced by Commodore and other manufacturers.

The PET also has a fully programmable bi-directional parallel interface called the “User” port, which allows the PET to connect and control almost any device one could dream up! The greatest feature, however, is the friendly READY prompt, and the well-laid out keyboard with graphic characters only a keypress away! Pictured here is the PET 4016.

Interestingly, although Commodore provided 8, 16, and 32k versions of their PET 2001 and 3001 series, they had a hard time getting people to purchase higher memory versions as an upgrade. It seemed that people were soldering in their own memory chips onto PET 2001 and 3001 8k and 16k models to upgrade them to 32k. To help prevent this, Commodore sold many PET 4008 and PET 4016 models with the empty memory sockets punched out and destroyed! This encouraged those who wanted more memory to upgrade to the 4032 instead of doing it themselves.

Gallery:

source: zimmers.net

Commodore PET 2001-8C (Chiclet): Brothers of the same father

August 25th, 2014 No comments

These are my two Commodore PET 2001-8C (Chiclet). They are two different models, below i will list the differences.

On the left:

  • Different front Label.
  • PET Motherboard ASSY 320132
  • Different Copyright Label on motherboard (1978)
  • Uses the 2114 ram ic for the Main memory and for the Video ram.
  • CRT tube with green phosphor.
  • The transformer, the big electrolytic capacitor and the power connector are different.
  • Datassette Motherboard ASSY 320275-B (1978)

On the right:

  • Different front Label.
  • Motherboard ASSY 320008
  • Different Copyright Label on motherboard (1977)
  • Uses the MOS 6550 ram ic for the Main memory and for the Video ram.
  • CRT tube with white phosphor.
  • The transformer, the big electrolytic capacitor and the power connector are different.
  • Datassette Motherboard ASSY 320109.E (1977)

Commodore PET 2001-8C (Chiclet Keyboard) MOS 6550 Ram version

August 24th, 2014 No comments

This Commodore PET 2001-8C also includes a homemade Power Amplifier to hear the sound of some games that use the pin CB2 of the User Port as audio output.

Also is included a reset button and two mini-led (Red / Green) that display the data (Save / Load) when using the tape recorder.

Some photos of the Commodore PET 2001-8C:

Copyright label on the motherboard:

Some photos of the repairing and cleaning:

Commodore PET 2001 (Chicklet) Repair datassette.

Defects:

  • Doesn’t load any more.

Repair:

  • Replace motor.
  • Replace belt.
  • Azimuth adjustment.

Thanks to Manosoft for the spare parts (white datassette, the same model of the black one)

Commodore PET 2001 (Chicklet) Repair.

Defects:

  • Wrong chars on the screen.
  • Memory problems.

Repair:

  • Replaced all MOS 6550 main ram with an 6550 Ram Adapter by xAD & Manosoft (only 2 x MOS 6550 was faults)
  • Replaced 1 x MOS 6550 Video Ram with a spare one from the main ram.

Video of Galaxy Invaders with Sounds:

from Wikipedia homepage:

The Commodore PET (Personal Electronic Transactor) was a home/personal computer produced in 1977 by Commodore International. A top-seller in the Canadian and United States educational markets, it was Commodore’s first full-featured computer, and formed the basis for their entire 8-bit product line.

Read more…

Commodore PET(CBM) 3032 Repair

May 25th, 2014 No comments

Commodore CBM/PET 3032 Motherboard Repair.

Defect:

  • Garbled screen and then “Illegal Quantity Error” message or 31 Bytes free

Replaced parts:

  • Replaced 1 x NE555 (A2)
  • Replaced 2 x Unstable RAM 4116 (I2/I3)
  • Replaced 1 x 74LS153 (E4)

Repaired for a friend a Commodore CBM 8296 Motherboard

March 12th, 2014 1 comment

Repaired for a friend a Commodore CBM 8296 Motherboard.

Defect:

  • Black screen of death without startup beep.

Replaced parts:

  • Replaced PLA [UE6] with a OTP EPROM 27C512R 70ns + Adapter.
  • Replaced PLA [UE5] with a original one MOS 324744-01
  • Replaced [UC8] 3-State Driver Bus MOS 65245 (74LS245)

Restoring & Repair a Commodore 8296 (TAN Case)

January 25th, 2014 3 comments
Commodore 8296 (TAN Case)

The conditions of this Commodore 8296 (TAN Case) are really bad. The CBM 8296 is left for over 25 years in a dovecote.

The cleaning, repairing and restoration have taken a very long time, but the result is more than acceptable.

The comparison (before / after):

Defects:

  • The Commodore 8296 was completely dead (Black screen of death).
  • Little problems of CRT geometry.

Replaced parts:

  • Replaced PLA U6 with a OTP EPROM 27C512R 70ns + Adapter
  • Replaced the ROM 2 x 2764 Eprom with 1 x 27C128 Eprom (spare parts from a original cbm pcb)

Note:

I have replaced the original ROM (2 x EPROM) pcb because the PLA adapter is fat. I could insert a small castle (photo) between the ROM pcb and the Main Motherboard but in this time i have prefered to replace with a single Eprom.

Gallery of repair and cleaning:

Repaired for a friend a Commodore CBM 8296-D Motherboard

January 6th, 2014 No comments

This is a Commodore CBM 8296-D Motherboard repaired for a Friend.

Gallery of the repair:

Defect:

  • Black screen of death without startup beep and after replacing U5 and U6 black screen of death with startup beep.

Replaced parts:

  • Replaced PLA U5 with a original PLA MOS 324745-01.
  • Replaced PLA U6 with a OTP EPROM 27C512R 70ns + Adapter
  • Replaced a dual FlipFlop 74LS74 UD4.

* The replacement of the two PLA has already been made earlier by my friend.

Restoration & Repair of a Commodore 8032-SK (Gold Label)

January 6th, 2014 1 comment
Commodore 8032-SK (Gold Label)

The conditions of this Commodore 8032-SK (Gold Label) are really bad. The CBM 8032-SK is left for over 25 years in a dovecote.

The cleaning, repairing and restoration have taken a very long time, but the result is more than acceptable.

The comparison (before / after):

Defects:

  • The Commodore 8032-SK was completely dead (Black screen of death).
  • Little problems of CRT geometry.

Repair:

  • Replaced the CPU 6502.
  • Yoke calibration of the CRT

Gallery of repair and cleaning:

Cleaning & Repairing a Commodore PET 2001-8C

October 31st, 2013 No comments
It Works!

This gallery shows some stages of repairing the Commodore PET 2001-8C

Two months have passed since i have received my Commodore PET 2001-8 Chicklet exchanged for a Sharp MZ-80K, was the day 28/08/2013.

The motherboard was in disastrous conditions, it took two months and a lot of patience to repair it.

Defect:

  • Garbled characters at boot.
  • Tape Recorder (Datassette) Motor Tired.

Replaced parts and various repairs:

A large number of short circuits visible and not visible (under the ic sockets)

  • 2 x 6540 ROM Basic 1.0
  • 2 x 74LS00
  • 3 x 74LS157
  • 1 x 7805
  • 2 x Electrolytic Capacitor / Tantalum.
  • 1 x Tape Motor
  • 16 x 2114 RAM

I want to dwell on the ram, i noticed that the PET 2001-8 Chicklet does not digest very well all ram.

These ram don’t work properly for my PET 2001-8 Chicklet:

  • TESLA 2114 (2/8)
  • MM2214N
  • SY2114-2
  • HKE2114L-2

I had to buy several stocks of ram in 2114 to find the right ram that work correctly. The ram that work very well are the ELCAP 2114L-3.

I have to thank Andrea Pierdomenico for the ROM test on his PET 2001-8C and Alessandro Polito. for the exchange.

Commodore PET 2001-8C (Chiclet Keyboard)

October 31st, 2013 No comments
Commodore PET 2001-8C (Chicklet Keyboard)

Autopsy:

This Commodore PET 2001 also includes the Expansion Memory ExpandaMem made by CompuThink

from Wikipedia homepage:

The Commodore PET (Personal Electronic Transactor) was a home/personal computer produced in 1977 by Commodore International. A top-seller in the Canadian and United States educational markets, it was Commodore’s first full-featured computer, and formed the basis for their entire 8-bit product line.

In the 1970s Commodore was one of many electronics companies selling calculators designed around Dallas-based Texas Instruments (TI) CPU chips. However, in 1975 TI increased the price of these components to the point where the chip set cost more than an entire TI calculator, and the industry that had built up around it was frozen out of the market.

Commodore responded to this by searching for a chip set they could purchase outright. They quickly found MOS Technology, who were in the process of bringing their 6502 microprocessor design to market, and with whom came Chuck Peddle’s KIM-1 design, a small computer kit based on the 6502. At Commodore, Peddle convinced Jack Tramiel that calculators were a dead-end. In September 1976 Peddle got a demonstration of Jobs and Wozniak’s Apple II prototype, when Jobs was offering to sell it to Commodore, but Commodore considered Jobs’ offer too expensive.

Tramiel demanded that Peddle, Bill Seiler, and John Feagans create a computer in time for the June 1977 Consumer Electronics Show, and gave them six months to do it. Tramiel’s son, Leonard, helped design the PETSCII graphic characters and acted as quality control. The result was the first all-in-one home computer, the PET, the first model of which was the PET 2001. Its 6502 processor controlled the screen, keyboard, cassette tape recorders and any peripherals connected to one of the computer’s several expansion ports. The PET 2001 included either 4 kB (2001-4) or 8 kB (2001-8) of 8-bit RAM, and was essentially a single-board computer with discrete logic driving a small built-in monochrome monitor with 40×25 character graphics, enclosed in a sheet metal case that reflected Commodore’s background as a manufacturer of office equipment. Designed on an appliance computer philosophy similar to the original Macintosh the machine also included a built-in Datassette for data storage located on the front of the case, which left little room for the keyboard.

The data transfer rate to cassette tape was 1500 baud, but the data was recorded to tape twice for safety, giving an effective rate of 750 baud. The computer’s main board carried four expansion ports: extra memory, a second cassette tape recorder interface, a parallel port (mainly used for disk drives and printers) and an IEEE-488 port (mainly used for modems).

The PET 2001 was announced at the Winter CES in January 1977 and the first 100 units were shipped later that year in October. However, the PET was back-ordered for months and to ease deliveries, early in 1978 Commodore decided to cancel the 4 kB version (also because the user would be left with barely 3 kB of RAM).

source: wikipedia

Repairing a Commodore CBM 610

October 26th, 2013 2 comments
Components replaced

This gallery shows some stages of repairing the Commodore CBM 610.

Defects found on the Commodore CBM 610:

  • Random raster lines on the screen.

Components replaced:

  • 2 x 74LS245
  • 1 x 74S32
  • 1 x 74S05
  • 1 X 74LS14
  • 2 x Capacitor 22uf 10v
  • 2 x Capacitor 1uf 50v

I have passed three weeks of suffering for repairing this CBM 610. The finding of the fault is not has been easy, the key component of the failure was the IC 74S05 (U96) followed by the other components.

Repairing & Cleaning a Commodore CBM 610

September 29th, 2013 No comments
Characters rom & CPU 6509A

This gallery shows some stages of the cleaning and repairing the Commodore CBM 610.

Defects found on the Commodore CBM 610:

  • Black Screen of Death.
  • Garbage characters on the screen.
  • Keyboard Yellowed.
  • Filter capacitor exploded.

The black screen of death was fixed by replacing the CPU MOS 6509A and the problem of garbage characters on the screen was fixed by replacing the ROM characters with a EPROM 2532 suitably programmed.

The yellowed keyboard was replaced with a new one in good condition of the Commodore CBM 710. I like Commodore. What will be the difference of a CBM 710 and a CBM 610 keyboard? nothing, are the same! no! on the keyboard of the CBM 710 has two wires reversed! (brown/red) ;-D

The filter capacitor exploded has been removed.

Commodore CBM 610

September 29th, 2013 No comments

Commodore CBM 610

Autopsy:

from Wikipedia:

The Commodore CBM-II series was a short-lived range of 8-bit personal computers from Commodore Business Machines (CBM), released in 1982 and intended as a follow-on to the Commodore PET series.

The CBM-II had two incarnations, the P series (P = personal, or, home use) and the B series (B = business use). The B series was available with a built-in monochrome monitor (hi-profile) with detached keyboard, and also as a single unit with built-in keyboard but no monitor (lo-profile). These machines were known as the “Porsche PETs” for their unique styling.

The P series used the VIC-II 40-column color video chip like the C64. It also included two standard Atari-style joystick ports. The 6509 CPU ran at 1 MHz in the P series due to the use of the VIC-II chip.

The B series used a 6545 CRTC video chip to give an 80-column “green screen” monochrome output more suitable for word processing and other business use than the VIC-II’s 40-column display. Most models have the Motorola 68B45 installed which is a pin compatible variant rather than the MOS 6545A1 2 MHz part. On the B series the 6509 CPU ran at 2 MHz.

Features common to both the P and B series included an MOS Technology 6509 CPU, an enhanced version of the venerable 6502, that was capable of addressing up to 1 megabyte of RAM via bank switching (however, no CBM-II model came with more than 256 kilobytes of RAM, 1/4 megabyte). The sound chip was the 6581 SID, the same one that was used in the popular Commodore 64 (C64) but with some limitations as it was over-clocked to 2 MHz. Additionally, the CBM-II had an industry-standard RS-232 serial interface and an IEEE-488 parallel bus (for use by disk drives and printers) just like the PET/CBM series. The CBM-II’s built-in operating system used an enhanced version of CBM BASIC version 4.0.

An optional Intel 8088-based coprocessor board allowed the CBM-II series to run CP/M-86 1.1 and MS-DOS 1.25; however, the computers were not IBM PC compatible and very little, if any, software taking advantage of this capability ever appeared. The coprocessor board only ran on hi-profile machines due to power supply and mechanical spacing requirements.

The production naming within the United States and Canada was the B128/B256 and CBM128-80/CBM 256-80 while in Europe they were known as the 600 and 700 series respectively (no “B” in front of the model number). The P machine was known worldwide as the 500 series. There are prototype models though such as the B500 (earlier B128 design) and B700 (earlier CBM 128-80/CBM 256-80 design) known to exist.

Due to the popularity of the C64, the P series was cancelled in the United States before it could be officially released; however, a few dealers who received preproduction units sold them. As these computers had not received approval from the Federal Communications Commission, this caused legal problems for Commodore. The units were recalled and destroyed, but a very small number exist today, in private collections. At least one model, the P500, was commercially released in Europe but only sold in small numbers.

source: wikipedia

Commodore P500 (PET/CBM-II) pre-Production Prototype

September 18th, 2013 No comments
Commodore P500 (PET-II) pre-Production Prototype

Autopsy:

I have received this computer to be repaired for a friend with a classic startup fault; the Black screen of Death.

After careful analysis of the problem and thanks to Alessandro Polito for the test, the failed component was the CPU 6509.

from Wikipedia:

The Commodore CBM-II series was a short-lived range of 8-bit personal computers from Commodore Business Machines (CBM), released in 1982 and intended as a follow-on to the Commodore PET series.

The CBM-II had two incarnations, the P series (P = personal, or, home use) and the B series (B = business use). The B series was available with a built-in monochrome monitor (hi-profile) with detached keyboard, and also as a single unit with built-in keyboard but no monitor (lo-profile). These machines were known as the “Porsche PETs” for their unique styling.

The P series used the VIC-II 40-column color video chip like the C64. It also included two standard Atari-style joystick ports. The 6509 CPU ran at 1 MHz in the P series due to the use of the VIC-II chip.

The B series used a 6545 CRTC video chip to give an 80-column “green screen” monochrome output more suitable for word processing and other business use than the VIC-II’s 40-column display. Most models have the Motorola 68B45 installed which is a pin compatible variant rather than the MOS 6545A1 2 MHz part. On the B series the 6509 CPU ran at 2 MHz.

Features common to both the P and B series included an MOS Technology 6509 CPU, an enhanced version of the venerable 6502, that was capable of addressing up to 1 megabyte of RAM via bank switching (however, no CBM-II model came with more than 256 kilobytes of RAM, 1/4 megabyte). The sound chip was the 6581 SID, the same one that was used in the popular Commodore 64 (C64) but with some limitations as it was over-clocked to 2 MHz. Additionally, the CBM-II had an industry-standard RS-232 serial interface and an IEEE-488 parallel bus (for use by disk drives and printers) just like the PET/CBM series. The CBM-II’s built-in operating system used an enhanced version of CBM BASIC version 4.0.

An optional Intel 8088-based coprocessor board allowed the CBM-II series to run CP/M-86 1.1 and MS-DOS 1.25; however, the computers were not IBM PC compatible and very little, if any, software taking advantage of this capability ever appeared. The coprocessor board only ran on hi-profile machines due to power supply and mechanical spacing requirements.

The production naming within the United States and Canada was the B128/B256 and CBM128-80/CBM 256-80 while in Europe they were known as the 600 and 700 series respectively (no “B” in front of the model number). The P machine was known worldwide as the 500 series. There are prototype models though such as the B500 (earlier B128 design) and B700 (earlier CBM 128-80/CBM 256-80 design) known to exist.

Due to the popularity of the C64, the P series was cancelled in the United States before it could be officially released; however, a few dealers who received preproduction units sold them. As these computers had not received approval from the Federal Communications Commission, this caused legal problems for Commodore. The units were recalled and destroyed, but a very small number exist today, in private collections. At least one model, the P500, was commercially released in Europe but only sold in small numbers.

source: wikipedia

Repair two Commodore CBM 8296 with Black screen of Death

September 9th, 2013 No comments

These two computers had the classic fault: Black screen of Death.

The first one was repaired by replacing a ram chip (4264) partially interrupted, the other one had One of the two chip PLA dead.

I have to thank my friend Andrea for providing me a motherboard of a 8296 for spare parts, where i have recovered the PLA which i needed.