Z8001 and Z8581 chips

Already owned.

Two 74LS373, two 74LS245

I have these. I may change them for HCT versions, to reduce power a bit. And to see if the board still works with HCT.

Printed circuit board

2025-09-20 Arrived in the post! 

EPM7128STC100-15

This was very generously supplied with the PCB, by Jaques. Merci! Some of the corner pins have been bent in transit, despite being in a sturdy box. Maybe it rattled onto the sides? Not a disaster, I am able to carefully push them back into place. I would have liked a microscope and a hotplate to help me do this. I have mounted it by hand, and it was hard to do. I need to clean it up with IPA and inspect with a microscope.

CY62157ELL-45ZSXI

This 512k x 16 bit SRAM is rated at 4.5 to 5.5 volts VCC, perfect for 5V technology. They cost about £5 from suppliers, but eBay is often much more expensive. This tiny chip provides as much RAM as the 32 DRAM chips in the original design, in a fraction of the space. I have mounted it by hand.

I ordered two CY62157ELL-45ZSXI chips (one for spare, or another project), and they have arrived.

Two 2K ROM chips (2716)

I have one of these,  and over a hundred 64K EPROMs! Small devices are harder to find and often dearer than larger chips, but sockets are only 24 pins. I would like to make adapters so that I can fit larger, and possibly EEPROM, memories. The AT28C16 is a 24-pin EEPROM. An adapter would allow larger memories, allowing the board to boot directly into a monitor or BASIC, without the need for loading by a host PC.

I ordered and received two PQ2816 chips. These will allow me to get started without having to make adaptor boards. These are pin compatible, pin 21 being VPP or /WR, and pulled up on the board.

2K SRAM chip

Ordered and received 4 chips.

Silver solder and flux in a syringe

This makes nicer joints than the usual lead-tin solder. I don't use lead-free solder for hobby work, because it does not make joints as easy as leaded. I think the environment can cope with my few hobby boards. These have arrived from eBay. It turned out to be silver-tin, no lead. I didn't find it was very 'wet', so it reverted to normal lead-tin solder..

Crystal, 12 MHz

I have a 6 MHz processor. Low-height crystals are less prone to damage. I have 12 MHz.

DIP20, DIP24, and DIP18 sockets

I used two DIP24 sockets for the DIP48 CPU. All sockets fitted.

Various SMD passives

I usually work in labs with access to reels of these things, but I am between contracts right now.
I don't have access to surface-mounting equipment either, so I made do with what I have at home. Jacques told me that R25 is 22 Ohms, all the others are 10k.

2025-10-11

Ordered 0603 resistor and capacitor kits, and a few 0805 capacitors, from eBay. All have been fitted.