Explanation of how it work the program “RAM3_RAMFAIL_BAS” written by Dominic Brown in the 1990 in Super Basic for the Sinclair QL which is used to calculate what the RAM on the Sinclair QL is broken, you need to use the MINERVA ROM (RAM PassCheck).

I tried to explain how it work and i have rewrote the software in a “language” a bit more modern ;-D

MINERVA OUTPUT EXAMPLE:

——————————————
WRITE: 5 4 8 C 4 8 7 8
READ: 5 C C D 5 C C D
ADDRESS: 0 0 0 3 2 0 0 0
——————————————

HEX WRITE: 54 8C 48 78
HEX READ:  5C CD 5C CD

Convert the numbers in decimal:

DECIMAL WRITE: 84 140 72 120
DECIMAL READ:  92 205 92 205

You have to make a xor in pairs (write & read)

XOR: 84 XOR 92 = 8
XOR: 140 XOR 205 = 65
XOR: 72 XOR 92 = 20
XOR: 120 XOR 205 = 181

Now you need to do an OR with the result of the XOR starting with “0″ and continuing with the result of every OR

OR: 0 OR 8 = 8
OR: 8 OR 65 = 73
OR: 73 OR 20 = 93
OR: 93 OR 181 = 253

Convert the final result of the OR in Binary.

DECIMAL: 253
HEX: FD
BINARY: 11111101

Follow the table to find the faulty ram. Pay attention to the memory address.

1: BAD Ram
0: GOOD Ram

BINARY = 1     1     1     1     1     1     0     1

IF < $30000 (ADDRESS) = IC8  ,IC7  ,IC6  ,IC5  ,IC4  ,IC3  ,IC2  ,IC1

IF > $30000 (ADDRESS) = IC16 ,IC15 ,IC14 ,IC13 ,IC12 ,IC11 ,IC10 ,IC9

IF > $40000 Faulty ram is in expansion memory.

The Original Program (ram3_ramfail.bas) was written for the SINCLAIR QL in SUPER BASIC language by Dominic Brown (1990).
Documentation of how it work by Xad/Nightfall (2015).
Thanks to my friend for the support.

Faulty Ram Decoder Changelog:

• v0.1: First Release.
• v0.2: Added a message (Faulty ram is in expansion memory) if the Address > $40000.

Faulty Ram Decoder Online: http://www.nightfallcrew.com/minervaram

Download:

• Faulty Ram Decoder v0.1 PHP Script (996)
• Faulty Ram Decoder v0.2 PHP Script (1045)

Sinclair QL #1 Repair

Defect:

• White Screen (RAM problem)

Replaced parts:

• Replaced 3 x 4264 RAM

Note:

I took the opportunity to install the Minerva Rom v1.98 to identify the faulty ram. Thanks to the Minerva ROM i have identified 2 of 3 Ram failed.

• Ram Location $1F340 (IC9)
• Ram Location $3D040 (IC10)
• Ram Location $30910 (IC16)

Sinclair QL #2 Repair

Defect:

• White Screen / Black Screen / Garbage Screen / Annoying Background Sound

Replaced parts:

• Voltage regulator (7805) fault. In input we have 9v and in output 9v instead of 5v.

Note:

Incredibly nothing is exploded ;-D

Autopsy:

12►

The Mivar 9BN2V it’s a 9 inches B/W CRT screen with 16 programs preselection with a electronic tuning for each program. It can be powered even with a 12volt and has a headphone jack.

Mivar is an Italian TV-set manufacturer. It was founded by entrepreneur Carlo Vichi in 1945 in Milan. Mivar used to produce radios and CRT televisions, but now produces only LCD LED televisions. Mivar is the last Italian factory of televisions. Their factory is in Abbiategrasso (20 km from Milan).

Since the 80s until 2000 in Italy Mivar TVs have had a very wide spread, in fact these televisions were present in almost every Italian house, in the Italian TV Studios, in schools, hospitals, hotels and prisons, because these CRT TVs were good, cheap, robust and durable.

When the market decided to focus on the LCD TVs, Mivar was unprepared and had serious difficulties. But thanks to the tenacity of the master Carlo Vichi, Mivar introduced in 2010 some new attractive and competitive LCD-CCFL TVs, and in 2011 some new LCD-LED TVs. The televisions made today by Mivar are also particularly simple and rational, with a particular Italian design and front speakers for better sound. Today’s Mivar TVs are all made in Italy.

source: wikipedia

Autopsy:

12►

from Wikipedia:

The Sinclair QL (for Quantum Leap), was a personal computer launched by Sinclair Research in 1984, as the successor to the Sinclair ZX Spectrum. The QL was aimed at the hobbyist and small business markets, but failed to achieve commercial success.

The QL was originally conceived in 1981 under the code-name ZX83, as a portable computer for business users, with a built-in ultra-thin flat-screen CRT display (similar to the later TV80 pocket TV), printer and modem. As development progressed, and ZX83 became ZX84, it eventually became clear that the portability features were over-ambitious and the specification was reduced to a conventional desktop configuration.

Based on a Motorola 68008 processor clocked at 7.5 MHz, the QL included 128 KB of RAM (officially expandable to 640 KB) and could be connected to a monitor or TV for display. Two built-in Microdrive tape-loop cartridge drives (first seen as a peripheral for the Sinclair ZX Spectrum) provided mass storage, in place of the more expensive floppy disk drives found on similar systems of the era.

Interfaces included an expansion slot, ROM cartridge socket, dual RS-232 ports, proprietary QLAN local area network ports, dual joystick ports and an external Microdrive bus. Two video modes were available, 256×256 pixels with 8 RGB colours and per-pixel flashing, or 512×256 pixels with four colours (black, red, green and white). Both screen modes used a 32 KB framebuffer in main memory.

The hardware was capable of switching between two different areas of memory for the framebuffer, thus allowing double buffering. However, this would have used 64 KB of the standard machine’s 128 KB of RAM and there is no support for this feature in the QL’s original firmware. The alternative and much improved operating system Minerva does provide full support for the second framebuffer.

source: wikipedia