Friday, 14 October 2016

PET 2001TEST for 6540/6550

I had some trouble with the 6540-ROMs in my PETs and built an special adapter to read them in my EPROM-burner.
But it's not possible to read them in my TL866, Merlin/Promenade C1 and the Tiny Eprommer :(
The 6540 need a clock to operate correctly!

I decided to code a test-kernel that verifies the 8-bit-checksums in the PET ;)
Also I appended a RAM-test for the whole 8kB.
You have to burn the image in an EPROM and plug it with an adapter in the H7-socket.
It also runs in a 2532-EPROM (upper half) in a 2316B-board in the H4-socket.

Download Image: 2001TEST V1.0

YouTube: 2001TEST in action ;)

The test reads the 8-bit-checksums (without carry) from the ROMs in H1 - H6.
It verifies the checksums with the romsets 6540-011 to 6540-026.
For testing the 6540-018 or 6540-026, just plug it in the H6-socket.
The ROM-test needs no RAM to run - only the screen-memory for visibility ;)

2001TEST also checks the RAMs with 55 / AA in a continous loop.
But it's not possible to recognize the I or J chip because the test needs 2047 bytes and there is only 1 byte space left ;)

Wednesday, 24 August 2016

Schematics for the MAX 6566-6567 adapter

I just draw the schematics for the VIC II-adapter in my MAX.
If you have any questions or find an bug - please write me...

Here it is:

PDF: MAX-6566-Adapter.pdf

Saturday, 6 August 2016

Max Machine 6566-replacement-pcb finshed!

A few days ago I finished my replacement board with a 6567 for the broken 6566 in my MAX - and it works without any problems!

I built it on a prototype-pcb because I only need one board. It fits directly in the metal-cage of the vic, but you have to leave it open. The 6567 has no cooling now - but I don't use my MAX for long game sessions with radar rat race ;)

In the future I will draw the schematic in eagle and if anybody needs a replacement - just write me...

New original manuals for me ;)

I'm very lucky!

I just got these two original mos-manuals (very cheap):

Wednesday, 20 July 2016

I got a MAX machine - but with dead 6566 :(

I got a Max machine from a seller in tokyo in unknown condition for a fair (not cheap) price.
After checking the hardware I found the problem: The 6566 is dead - it doesn't divide the dotclock by 8.
I tried a 6567 on a breadboard as divider - and the machine runs (without picture).

Now I designed a 6566 replacement with a 6567:

- 74373 to isolate the A0 to A5 outputs with RAS
- 74373 to isolate A12 and A13 with CAS
- 74245 to tristate the A0 to A5 inputs in the VIC
- 7404 to invert AEC for the 245

I build this on a breadboard:

...and it works ;)

Now it's time to design a layout for an 6566/6567 adapter that fits in the 6566 socket.

Wednesday, 17 February 2016

Again a new Commodore ;)

Today my brand new Commodore LED-watch arrived from the USA.
Unbelievable - it's originally wrapped and totally unused since the Seventies!

After changing the batteries and adjusting the time:

...and it has the date:

The display shows the time only if I press the button for about two second to save energy.
If I press longer it shows the seconds.
If I press fast twice it shows the date.

...a nice little toy from the seventies for me ;-)

Saturday, 23 January 2016

A new Commodore for my collection!

I am very lucky: I got a fully working chessmate with PSU

The machine was built in 1979 - with 2 "very large" 2111 SRAM (256x4) = 256 bytes
and the 6530-024 RRIOT with the 1kB microchess-code from Peter Jennings.
The CPU is the 6504 - a 6502 with limited address lines: