The Issue 1.5 ZX Spectrum and the "Dead Cockroach" Mod

[@HappyLittleDiodes]

Thanks for watching and as always, if you spot anything incorrect please comment, accuracy of information is really important on this channel

[@flatduckrecords]

Fascinating, thanks for this detailed (and very clear!) walk-through of the mod. Great work.

[@HappyLittleDiodes]

Thanks! Enjoyed this one

[@bobbus_74]

Having just got my first ever 1.5 recently, this video really shed some light on Sinclair's cost-saving work arounds! Great video mate.

[@SteDubya]

This was very informative. Thanks for going into so much detail.

[@djwilduk]

Very well explained and presented.

[@HappyLittleDiodes]

Glad it was helpful!

[@donnaedwards1228]

What a great video, so glad I stumbled across this channel. 👍🏼

[@JohnSmith-bh4zx]

Another really interesting video, well done.

[@HappyLittleDiodes]

Thanks John

[@albertoernestini6279]

Thanks for this nice and interesting video. You're great!

[@philoffhistree]

great info and dont think anyone else has explored it either yet

[@HappyLittleDiodes]

There are some websites out there that go into some detail. There is more to learn but it would be a long video, maybe one for a Patreon blog post!

[@charlesjmouse]

Thank you. I wonder why the original ULA had separate handlers when one could do both jobs? Seems rather un-Sinclair like.

[@HappyLittleDiodes]

Maybe some limitation of the modular construction of the ULA? I'm not sure! The ULA book may have some insight

[@darren6202]

This was useful. Thank you. - My issue with the issue 1 ULA is that a connected Interface 1 doesn't work - i.e. it doesn't recognise the *CAT 1 command until you apply the dead-cockroach mod.

[@HappyLittleDiodes]

Yes I suppose in order to use the issue 1 ULA you should be on an issue 1 or 2 PCB with no spider mod and a dead cockroach installed to get proper function

[@andygozzo72]

pretty sure i have one of these, somewhere, in a dktronics keyboard case!

[@1107ml]

Hi I have a issue 1.5 ,,, but don't have the chip ! I will need this to finish this computer of , do you know where I can source the little breadboard and chip Thanks 😊

[@HappyLittleDiodes]

You could make it up yourself, try eBay for the chip!

[@andygozzo72]

? you mean an issue 2 board with a issue 1 ula? and no mod? likely the original ula has been replaced at some time with an earlier version....also both issue 1 and 2 ulas need a transistor adding to the iorqula line to correct io port problems , this was usually fitted to issue 2 machines

[@zoeyzhang9866]

Nice content pal👍! Wondering if any PCBs you may need when repairing? We'd love to give our support and achieve any collabs together. (PCBWay)

[@HappyLittleDiodes]

Thank you for the kind comment