The Sinclair QL Forum

https://www.ebay.co.uk/itm/223046561834

Never seen one with markings shown (Plessey) and dated 1990 week 29.

Don't think the Commodore 64 or Atari used them though

Hi!

Thanks for flagging-up this sale. I picked-up a couple to replace dead MDV ULA's in some of my ageing units - just to see whether they were legit...

They arrived promptly this morning and tested OK - I have a bare MDV unit with the original ULA replaced with a DIP socket (I know - not best practice, but seems to work), which allows me to easily swap-out ULAs.

I can't comment on the accuracy of the date-stamping (mine are also marked 'Plessey' - Batch code '9029'), but as they work, I've ordered another few for posterity - seems like they have plenty more in stock.

I wonder if these were produced aftermarket for the OPD and/or Merlin Tonto?

Good to hear they are legit, happened upon them when looking for Z8S18020 CPUs (20Mhz Z80 *).

Have bought a few items from same seller, well priced too, some stuff very cheap (HY29F400BT Flash). Has some other interesting 68000 stuff (68060/68030/68302/68340**).

*Update: BTW beware Z80 DIP40 20MHz PEC chips - feedback cites failure at 5 to 6MHz and suspects 4MHz parts.
**Update2: correction to misspell, was 68430, doh!.

ones' complement wrote:Good to hear they are legit, happened upon them when looking for Z8S18020 CPUs (20Mhz Z80).

Have bought a few items from same seller, well priced too, some stuff very cheap (HY29F400BT Flash). Has some other interesting 68000 stuff (68060/68030/68302/68430).

I found some 33MHz Z8S18033 - they passed all the test that I can throw at them - and being CMOS - you can run these at 20Mhz too

guy was selling them in Tubes of 10

Pr0f wrote:I found some 33MHz Z8S18033 - they passed all the test that I can throw at them - and being CMOS - you can run these at 20Mhz too

guy was selling them in Tubes of 10

I was going to build something like https://www.tindie.com/products/tindies ... board-kit/

Z8S18020 is OK for 18.43MHz system, have you tried running them at 36.86MHz? Author of SBC reckons it might be OK.

I have it running at 36Mhz in 2 retrobrew boards https://www.retrobrewcomputers.org/doku ... :sbc:n8:n8 and https://www.retrobrewcomputers.org/doku ... 80_mark_iv

and the little pocket computer here: https://www.tindie.com/products/tindies ... puter-kit/

In all cases using the clock doubler feature - so xtal is still 18.432MHz.

Lockdown led me to these things -

36.864MHz cool

Price on microdrive ULA just gone up

Update: But only 9 left...