Welcome at Collosumus.NET/ti99/project/micro computer

Building your own TMS99xx based modular micro computer

Sub project goal:

The goal of this project is to create a working micro computer that can communicate to any PC using a serial connection that will be relative easy to expand with add-on's so it can be used in hobby electronics. Basic components to be used include: CPU, (E)EPROM, SRAM, UART and of course some other components as well.

Updates:

11/26/2005 - RetrOS now has it's own site. For now, it's only thoughts and ideas.
03/05/2005 - Since I decided several days ago, that the newly to be written OS (called RetrOS) is to be compatible with Power9 and the Geneve, I added routines that can identify those systems and do the initialization accordingly. This also helps making debugging the code easier, at least I can see the output on a screen. ;-)
02/20/2005 - Added Eagle library file I created for the TMS9900/9995/99105A/99110A/V9938/V9958 and 61Cxxx that I use in my project.
02/17/2005 - I've come up with a name for my Modular computer project, the name is: Power9. This is of course with a big wink;-) to IBM.
02/16/2005 - The design has been updated to version 0.1.6. A download link can be found below under Downloads. It should work, it has been reviewed, but it's not tested yet. The board design will be sent to a PCB manufacturer later this week.
06/03/2003 - A very preliminary version of an Eagle schematic can be found at my FTP Server. It's non working and based on Jens-Eike's schematic he created a couple of years ago.
04/22/2003 - Added project related information.
04/18/2003 - Updated this website.

TODO list:

Making a board layout design in both Eagle and Gerber format.

Specifications:

Processor: Texas Instruments TMS9995.
Memory: 8 KB EPROM (2764) with basic firmware/OS and 56 KB SRAM (61512. Actually it's 64 KB (hence, an 61512 is used), but the first 8 KB is mapped to the EPROM.
Control: Jumpers so that the EPROM and/or SRAM can be disabled and switches for generating external interrupts.
Debug: LED's that indicate a certain status and LED's which can be controlled programmatically.
I/O interface: connector interface for I/O and future VDP.

Version control:

From 0.2.0 to 0.2.1: Added: Buffers to all signals going through CON1, Address bus, data bus, control bus IN, control bus OUT.
From 0.1.9 to 0.2.0: Added: IC10 (A). If connected, automatic first wait-state is prohibited, if not connected, an automatic first wait-state is added to each memory cycle regardless of the READY input, IAQ decode LED. If this LED is turned on, the CPU is fetching an opcode.
From 0.1.8 to 0.1.9: Corrected: Pull up resistor for RAMCE* that was obviousely drawn incorrectly, input and outputs for the LS156 (they should have numbered them Y0-Y7 ;-) ) and the GND and VCC connections for CON1.
From 0.1.6 to 0.1.8: Corrected: changed from LS138 to open collector version the LS156, corrected automatic 1st wait-state generation. (traditional EPROMS >100ns are too slow, so wait states needed). Added: Connector for future I/O board, jumpers to disable RAM and/or ROM. Again, thanks to Jens-Eike Hartwig.
From 0.1.5 to 0.1.6: Corrected: RAMCE* select from LS138 decoder, LED control, Package format (DIP-300 instead of DIL-600) for 61C512 SRAM. Added: jumpers for future enhancements of CRU based I/O. Thanks to Jens-Eike Hartwig for pointing some of these mistakes out to me.
From 0.1.4 to 0.1.5: Corrected several component packages in schematic to reflect proper package format in the board design.
From 0.1.3 to 0.1.4: Corrected CRU operation cycle in progress selection line (SYS_CRU*).

Downloads:

Schematic: Current version in JPG format.
Schematic: Current version in Eagle format.
Board: Current version in Eagle format.
Board: Current version in Gerber format.
Library: Eagle TMS99xx(x)/V99xx/61Cxxx symbols, packages and devices used in the project.
Component: Component list.
Software: Source code for EPROM. The source file is formatted for use with Microsoft's Visual Studio Editor.
Software: Binary file. For usage with an EPROM programmer. (in BIN format).
Software: Seaview's TMS99xx Development Kit. Cross assembler and linker for WIN32.