The code in /microcode-eeprom-with-flags adds functionality for a flags register to the microcode above to support conditional instructions. 8-bit computer microcode with flags register Adding more machine language instructions to the CPU.Ĥ.Reprogramming CPU microcode with an Arduino.You’ll probably want to watch the whole 8-bit computer playlist (see below) for this to really make sense, but the specific videos describing the code here are: The code in /microcode-eeprom-programmer is for programming a pair of EEPROMs to serve as an instruction decoder for an 8-bit breadboard computer.
Build an 8-bit decimal display for our 8-bit computer.The code in /multiplexed-display is for programming an EEPROM to be used to decode 8-bit values and drive a 4-digit 7-segment display. This is a good place to start if you’re looking for the fastest way to make sense of this repo: That software, along with the EEPROM programmer’s hardware are described in detail in the following video. The code in /eeprom-programmer is the basic programmer that programs a few bytes into the EEPROM and dumps the contents. But I’ve kept them separate to make it easier to find the exact code that goes with a particular video: 1. A lot of the code is duplicated since each sketch built on the previous ones. There are four different Arduino sketches that correspond to several YouTube videos. Since the Arduino doesn’t have enough pins to directly control all of the address, data, and control lines of the EEPROM, two 74HC595 shift registers are used for the 11 address lines (15 for the 28C256) and the output enable control line. This is a simple circuit for programming the 28C16, 28C64, 28C256, and similar parallel EEPROMs using an Arduino. ) that 4th page.This code and schematic are MIT licensed. I´ll pickup this task as soon as i am finished with the 4th page on my series about adjusting the DISK II drives, which i intend to complete this week ( i just need some time to make the pictures off from the scope and comment them. Partialy the circuitplan ( in separated parts ) has been started - but yet not commented that far. but you can get at least already now a impression of the card.ĮDITED UPDATE: The basic pictures have been made and i´m at least complete with the traces of the card.
DSK image of the software and i also mustĬreate a PCB-film of the card. I will of course translate to english too.
but i have allready completed the parts on the card and made a link to the german manual ( which i will have to reengineer that card to add theĬircuitplan. The new page about the programmer ( not finished yet ! ) will be located at:Īt the moment the page only contains some basic information. Its the second card in the list of special cards on that page. You can take a look to that card allready at: The different kinds of eproms requested a eprom specific plug on a so called "selection socket". it seems i will add this to the tasks on my "todo-list" and make within the next 2 weeks or so a documentation of that card ( including the shematic circuitplan ) and upload the disk-image to asimov.
together with the software in Applesoft.Īnyhow. I have one from the german company Springmann. I didn´t realize that to be such a problem, because most of the "old-fashioned" eprom programmer cards out of the apple II series can do the task of programming and reading of 27 eproms.