Mystery pcb??

[buzbard]

Does anyone recognize this? I found it in a second-hand shop.
It looks to be about the size of a VIC20 cartridge, so I assume it probably is.
Google hasn't given any clues, so I thought I'd try here.

[eslapion]

Considering what lines are used on the 'component side', it looks like a 16k RAM expansion. D0-D7 have a connection, so does BLK1-2 and CR/W. The connections for +5V and the ground are correctly positioned too.

It also takes the CPU clock and only uses 0.3" wide ICs so I'd say it's an attempt at making a 16k RAM expansion for the VIC which uses DRAM.

[buzbard]

Thanks eslapion, my suspicions were right then.
I'll probably never do anything with it.
I might just put it in a frame and hang it over my desk. It is a piece of art I guess.

[MCes]

MMMmmmmm......
I think that "data address buffering" wrote on it could be believed....
immagine a board similar at this
http://sleepingelephant.com/denial/wiki ... ic1020.gif

but that use 2 x 16pin flat-cables for DATA lines (may be 1 for Read, 1 for Write) and another 3 x 16pin flat-cables for address and control lines.
Note that the flat-cables has GND interleaved with signal lines

Probably all flat-cable was connected to an external motherboard (a system of I/O expansion, multi connector expansion, ram/rom expansion, ... custom....)

[Kweepa]

If you did decide to use it, you should probably fix the trace break coming off the third connector pad (in the upper image)

[eslapion]

MMMmmmmm......
I think that "data address buffering" wrote on it could be believed....
immagine a board similar at this
http://sleepingelephant.com/denial/wiki ... ic1020.gif

but that use 2 x 16pin flat-cables for DATA lines (may be 1 for Read, 1 for Write) and another 3 x 16pin flat-cables for address and control lines.
Note that the flat-cables has GND interleaved with signal lines

Probably all flat-cable was connected to an external motherboard (a system of I/O expansion, multi connector expansion, ram/rom expansion, ... custom....)

If it was then BLK 3 and 5 are missing and so are the lines for the 3k RAM expansion area. A pretty miserable I/O expansion at that...

The addresses are received into logic ICs because they are latched for multiplexing which is required for DRAM.

[MCes]

I think that this is a daughter board that has the task of buffering the bus (data/address/controls), this buffered signals will be output by flat cables connected as DIP, it generate cables that alternate a ground wire with a signal wire creating a sort of inter-shielding.
It is probable that this cables is connected to a motherboard but we have not other information for make ipotesis about the entire system.

I think this because address and data lines was directly connected as bus to a chips wall (IC1,2,3,4) that have 20pins, as a 74LS245.
IC5,6 could be the glue-logic to manage the buffer-system and DIP1,2,3,4,5 the flat-cable connector (an entire side of each are GROUND).

This cannot be a memory expansion cart because there is no chip (memory) that is reached, directly or indirectly, by both address and data lines.
It cannot be a dynamic memory expansion also because the pins of the chips wall don't meet with the pin of the multiplex that has 16pin (74LS257), and dynamic RAM chips appear to be not compatible with this footprint.
On the VIC 20 connector is not performed any refresh activity and the board appear to be too simply to perform it on-board.

For this reasons It appear to not be an memory expansion, especially a dynamic one

p_130427_03571.jpg (60.8 KiB) Viewed 2989 times

[eslapion]

This cannot be a memory expansion cart because there is no chip (memory) that is reached, directly or indirectly, by both address and data lines.
It cannot be a dynamic memory expansion also because the pins of the chips wall don't meet with the pin of the multiplex that has 16pin (74LS257), and dynamic RAM chips appear to be not compatible with this footprint.
On the VIC 20 connector is not performed any refresh activity and the board appear to be too simply to perform it on-board.

Good point.