In this post we will check some programs for CP/M and learn how to load your own programs on “RAM-disk”. External command POWER is intended to work with files in a RAM and the “RAM-disk”. It allows to view files, edit them, rename or erase them, as well as to [...]
Finally we reached the most exciting part – we will launch CP/M operation system on “UT-88″. This system was initially developed in 1975 by Gary Kildall of Digital Research, Inc. for Intel 8080 based computers. “UT-88″ is based on the Soviet analog of this processor (KR580VM80A), so it was possible [...]
In the previous post we learned how to launch the computer in full configuration. Lets see how it works and what commands MONITOR-F has. As you remember, Monitor-F can be launched from address F800H using the command 7 F800. MONITOR-F setups stack pointer, initialise some constants and variables in memory and [...]
I hope you enjoyed to play with minimal configuration of the computer. Now lets see how it can be launched in full configuration. “UT-88″ computer supposed to be build step by step, starting with minimal configuration and then adding additional blocks to extend its functionality. That’s why it is a [...]
In the previous post we learned how to launch the computer in the minimal configuration. Now lets see how it works in details. MONITOR-0 which is responsible for the computer work in the minimal configuration is allocated in the ROM in the range 0000H-03FFH. To launch it we just need to reset the [...]
To build “UT-88″ replica I created an extension board for DE1. I’ve added six 7-segments indicators and 16-keys keypad on it almost like original “UT-88″ in minimal configuration had. The board should be connected to GPIO_1 extention header of DE1 to avoid changes in the project. Just in case, I’ve [...]
I would like to start my blog with this computer. I’m going to make a replica of this computer using FPGA. But lets start from its history first. UT-88 is a hobbyist 8-bit computer that was build on CPU KR580VM80A which is a Soviet analog of a popular Intel 8080. [...]
I’m about to finalise my Rev.0 of the modern replica of the retro-computer “AGAT-7”. The next step will be Rev.A design with fixed mistakes, improvements and some new ideas. In this post I’m going to summarise the Rev.0 experience and share with you with some ideas for Rev.A. At the [...]
In my project of a modern replica of a retro computer “Agat-7” I needed to generate several different clocks. Some of them can be produced by the PLL built in FPGA, others are a simple division of the main clock. But there is another group of clock signals that are [...]
I organised a temporary place for my hobby when I moved the house. It quickly became a mess because it didn’t have any drawers or shelves there. So, finally, I’ve decided to build a decent place for my home lab. I didn’t want to spend a lot of money on [...]
My son got XBOX before Christmas and I couldn’t resist trying it. So, now I have some rest from my electronics hobby. Apart of this I’m building my hobby working place instead of the messy temporary one that I’ve used. I’ll do a post about it as well when it [...]
Some time ago I’ve got an old computer for free. Nothing happened when I tried to turn it on, so I assumed that the power supply is broken. It is a small IBM computer in a horizontal desktop case. It has a power supply integrated on motherboard. There are some [...]
Let’s go to the following part of the schematic. Today it is the CPU, the SRAM and the joysticks. Here it is: “Agat-7″ has 96Kb of RAM, so we need 128Kb SRAM chip. We can use 128K x 8bit or 64K x 16bit chips. The second option requires 9 more [...]
I need a logic probe to troubleshoot some of my designs. I didn’t want to reinvent a wheel, so I checked the existing designs. I found that the design from talkingelectronics.com is most suitable for my needs. The main benefits of this design are sound indication and 3rd LED (for [...]
At the moment I’ve completed the schematics and I’ve started to work on PCB layout. There are going to be some changes caused by discovered mistakes or better layout. So, please, treat it as a draft on this stage. Please, let me know if you notice any mistakes. Today we [...]
I’ve spend some time to debug STM32L based 140K “floppy-drive” for my “Agat-7” replica project. It is already perfectly workable in read only mode. I transferred it to SPI interface to save some FPGA pins and now I need only 5 pins instead of 12. For 840K floppy drive it [...]
HD44780-compartible LCD digital-alphabetical displays are very convenient to use in hobby projects. They exist in different sizes and are quite cheap. The most popular are 2 line modules with 16 characters per line (16×2). Also, 8х2, 16х1, 20х2, 20х4 and 40х2 modules exist. For my “AGAT-7″ retro computer project I [...]
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