Strange video problem

[craftsman1234]

Ouch, sorry to hear about the new problems you got.

The ram I got was labeled NEC 8402A5 μPD2114LC

Those *are* SRAMs. However, I've seen photos of NEC µPD2114LC in the 'net with '-5' behind the type, i.e. 500 ns. If there is no indication of access time behind a hyphen, this most probably means you got chips which are even slower than 500 ns.

Anyway, 500 ns are already too slow for the VIC-20. Take SRAMs with access time of 300 ns, if possible, which would be indicated by '-3' after the type. 400 ns (with '-4') might also work.

Just to add they all have -3 on them.

[Mike]

I took another look at the garbled display.

It is possible, that the VIC registers are wrongly initialised, so the screen display start address now points to uninitialised memory. For a short explanation, '@' and the checkerboard character are 0 and 255, respectively. You find this two-byte pattern quite often. When they're interspersed with other values, these are often remainders of the old content, when the VIC-20 was only switched off for a short time. At least the VIC-20 reset routine came as far as programming the VIC registers.

1. Is this a static picture, or do some of the characters change?

2. Does the image change, when you add/remove the +8K RAM expansion?

3. Does the VIC react to commands typed-in blindly (like POKE36879,8 - which should change background and border to black)

4. Could you provide good photos of the solder job (component side and solder side)?

[craftsman1234]

I took another look at the garbled display.

It is possible, that the VIC registers are wrongly initialised, so the screen display start address now points to uninitialised memory. For a short explanation, '@' and the checkerboard character are 0 and 255, respectively. You find this two-byte pattern quite often. When they're interspersed with other values, these are often remainders of the old content, when the VIC-20 is only switched off for a short time. At least the VIC-20 reset routine came as far as programming the VIC registers.

1. Is this a static picture, or do some of the characters change?

2. Does the image change, when you add/remove the +8K RAM expansion?

3. Does the VIC react to commands typed-in blindly (like POKE36879,8 - which should change background and border to black)

4. Could you provide good photos of the solder job (component side and solder side)?

I will recheck this when I get home but the effects were very similar with the 8k ram or the expansion board using different bank settings. The screens change each time and yes certain characters do quickly change. I have seen this on the 64 when 0 page is accessed to screen memory.

I'll try the Poke command and get close up's of the MB later today.

[craftsman1234]

2. Does the image change, when you add/remove the +8K RAM expansion?

3. Does the VIC react to commands typed-in blindly (like POKE36879,8 - which should change background and border to black)

4. Could you provide good photos of the solder job (component side and solder side)?

Nothing is different with the 8k plus expansion.

No response to the Poke commands.

Here are the pictures of my sloppy work.










Before I go and remove the socket I want to make sure to test the Ram that I have coming.