8052 CPU card for RC2014 Bus part 2

December 31, 2018

It’s been a while since I posted about the 8052 CPU card for RC2014 Bus and heres a update to where i got to with this interesting RC2014 project.

The original 8052’s are still available but originally used UV erasable EPROM or OTP PROM for their program memory. So instead I’ve been using a modern FLASH memory version of the 8052, a AT89C5252 with great success.

The original 8052-BASIC has was good but had a number of software bugs. Fortunately, there had been a number of improvements over the years and the version I’ve been using is V1.31 which can be found here:

8052-BASIC needs a couple of K’s of RAM to operate. For this I’ve been using a standalone 32K-byte SRAM card.

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New RC2014 boards: RS232 and 8052

April 24, 2018

I got a bumper box of PCB’s in the post today, just in time for Maker Faire UK 2018 this weekend (29th/30t April 2018).

Inside the box were some new RC2014 boards. The first two new PCB’s were my respins of a Z80 SIO/2 serial board and a Raspberry Pi Zero terminal board, as well as two brand new designs.

The first brand new board was a RC2014 RS232 breakout board allowing TxD1/RxD1 and/or TxD2/RxD2 serial signals from the RC2014 bus to be driven at RS232 levels.

The second brand new PCB was a new 8052 CPU board. This is a bit of an experimenters board as the 8052 bus architecture doesn’t directly map onto the Z80 bus architecture. When using the 8052 CPU some of the Z80 control bus signals (!M1, !MREQ, !IORQ etc.) will need pulling low via jumpers when attempting to make use of other cards. So why all the fuss. Well, the 8052 CPU does have the excellent the 8052-BASIC available which does make it a fun and a powerful (in 1980/1990 micro terms 🙂 ) system.