Component Substitution Due To The Worldwide Chip Shortage

For around a year now there have been reports of chip shortages affecting things like the automotive industry or high end graphics cards. This has extended to many other industries, including retro computing. With some components it has meant a sharp increase in price, and others have become impossible to buy. Even such staples as the humble AT27C512 ROM IC used in many RC2014 products has been hit hard. The following graph shows worldwide inventory levels of 27C512 at stockists such as DigiKey, Mouser, RS and the others

As of May 2022 the RC2014 kits which are affected most are;

  • RC2014 Micro
  • RC2014 Mini
  • RC2014 Mini CP/M Upgrade Kit
  • RC2014 Classic II
  • RC2014 Classic II CP/M Upgrade Kit
  • RC2014 Pro
  • Pi Zero Serial Terminal
  • IDE Hard Drive Module
  • DS1302 RTC Module
  • USB CDC Adapter

See below for specific ways this might affect you. In general, though, some kits are out of stock and likely to remain that way for several months. Others may have component changes to work around the shortages. This will not affect how the kit performs, but it may mean that some parts do not match exactly with the silkscreen, Bill Of Materials or schematic.

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it is likely that as time goes on, other parts will also become unavailable, or shoot up dramatically in price, so it is possible that other substitutions may happen at some point.

Please note that I am aware that some Chinese suppliers are showing large stocks of some components not available from mainline suppliers. Similarly, eBay sellers also have listings for some parts too. If you wish to go down this route and source your own parts, that is fine. You may also have parts in a drawer that have been pulled from other machines. Almost all of my PCBs are available, so feel free to source your own components if you wish.

RC2014 Micro

The RC2014 Micro used a 27C512 ROM, which was a 64k chip divided up in to 8 banks of 8k. Only the first and last bank were used (Bank 0 had 32k BASIC and bank 7 had SCM – although some people found the hidden Easter Egg inbetween).

The PCB has been redesigned as the RC2014 Micro+ and will take a 39SF010, which is a 128k flash ROM that has 4 extra pins. It will also support the 39SF020 and 39SF040 (256k and 512k respectively) if stock of the ‘010 runs short.

Despite the extra space, only the first 64k of ROM is available, and this is still divided in to 8 banks of 8k each with bank 0 and 7 being of interest.

RC2014 Mini

The RC2014 Mini used a 27C512 ROM, labelled R0000009 which was a 64k chip divided up in to 8 banks of 8k. Only the first and last bank were used (Bank 0 had 32k BASIC and bank 7 had SCM).

A smaller chip, the 27C256 which is 32k is being used until my stock runs out. This is divided up in to 4 banks of 8k and labelled R009. The jumper settings shown in the assembly instructions still work as expected.

RC2014 Mini CP/M Upgrade Kit

The RC2014 Mini CP/M Upgrade Kit uses a 27C512 ROM labelled R0881099 which is a 64k chip divided up in to 4 banks of 16k, where Bank 0 is 32k BASIC, Bank 1 is SCM with BASIC and CP/M, Bank 2 is CP/M, and Bank 3 is SCM.

While stock lasts the 27C512 will still be supplied. However, a swap to a 27C256 with just R088 may happen at some point in the future.

RC2014 Classic II

The RC2014 Classic II used a 27C512 ROM, labelled R0000009 which was a 64k chip divided up in to 8 banks of 8k. Only the first and last bank were used (Bank 0 had 32k BASIC and bank 7 had SCM).

The ROM Module PCB has been redesigned as the RC2014 Classic II+ and will take a 39SF040, which is a 512k flash ROM that has 4 extra pins. It will also support the 39SF010 and 39SF020 (128k and 256k respectively). Initially, a 39SF010 will be supplied, but may be swapped for one of the other two options if stock of the ‘010 runs short.

Despite the extra space, only the first 64k of ROM is available, and this is still divided in to 8 banks of 8k each with bank 0 and 7 being of interest. The ROM will still be labelled R0000009 and the banks still being selected by the same jumper positions.

Classic II CP/M Upgrade Kit

The RC2014 Classic II CP/M Upgrade Kit uses a 27C512 ROM labelled R0881099 which is a 64k chip divided up in to 4 banks of 16k, where Bank 0 is 32k BASIC, Bank 1 is SCM with BASIC and CP/M, Bank 2 is CP/M, and Bank 3 is SCM.

The ROM Module PCB has been redesigned as the RC2014 Pageable ROM+ and will take a 39SF040, which is a 512k flash ROM that has 4 extra pins. It will also support the 39SF010 and 39SF020 (128k and 256k respectively). Initially, a 39SF010 will be supplied, but may be swapped for one of the other two options if stock of the ‘010 runs short.

Despite the extra space, only the first 64k of ROM is available, and this is still divided in to 8 banks of 8k each with bank 0 and 7 being of interest. The ROM will still be labelled R0881099 and the banks still being selected by the same jumper positions.

RC2014 Pro

The RC2014 Pro uses a 27C512 ROM labelled 24886009 which is a 64k chip divided up in to 6 banks of 8k and 1 bank of 16k.

Whilst stock lasts, this 27C512 will still be supplied. A change to the RC2014 Pageable ROM+ Module (as seen above on the Classic II CP/M Upgrade Kit) with a physically larger chip, but still with the same ROM images may happen at some point.

Pi Zero Serial Terminal

Stock of the original Pi Zero 1.3 has been hard to get hold of for a while, although I know a lot of people still have a spare Pi knocking around in a drawer or old project somewhere, so this kit is still supplied. The SD card image for it is the original PiGFX written for the RC2014 using a Pi Zero 1.3 – However, if you have a Pi Zero W (the wireless version), or use jumper cables to connect to any other Pi, then there are more recent builds of PiGFX here which should support your Pi. https://github.com/fbergama/pigfx

IDE Hard Drive Module

The 82C55 used in this module has been unavailable for some time now. I have had these on order since October 2021, with deliver quoted for November 2021. This has varied up to May 2023, although is currently showing up as due for delivery at the end of June 2022. So they might be back in stock soon… but I’m making no promises until the chips are in my hands!

DS1302 Real Time Clock Module

Another one where the original DS1302 now seems totally unavailable. Delivery of the DS1302 is currently being quoted as May 2023. The surface mount version of the DS1302 was available for a while after the through hole one ran out, but this didn’t last long enough to design a board around. Currently looking at other options here.

USB CDC Adapter

The chip used on the CDC adapter is also on extended lead times, with March 2023 being quoted. Stock of these adapters has run out here, but other options are being looked at.

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