Sometime in the first quarter of 2006 i tried to recover my old
Prof80 CP/M Z80 System. It was equiped with a GRIP video card with fbas
output and some sort of serial or parallel keyboard input. (See prof80.de)
I found a monitor capable of displaying the grip output but it was to horrible to work with the system, low refresh rate and a horrible monitor, terribble keyboard. So i thought about connecting a state of the art LCD monitor, but how ?.
After doing some search, i found out that it is not so difficult to generate a VGA signal with FPGA's, so i ordered a board equiped with a xilinx XC2S200, the XSA-200 Board from XESS. I selected this board because it is small enough to fit onto an euro card (100 time 160 mm) and can be plugged into a simple socket using a raster of 2,54 mm.
The board has fast SRAM but i was never able to get it working.
So i build a small board equiped with fast static ram (cache ram
from old 486 boards, located under the FPGA board) as video ram, the
ecb connector, a serial interface and a buzzer. (Buzzer and the serial
interface are not yet implemented in the code).
This was the second time t tried to implement some functionallity in VHDL (see GIDE for ECB), and at least for me, it was not easy. I had a lot of trouble with timings, the ecb interface and so on. For the PS/2 struff, i used a feely available interface written by Daniel Quintero.
The card is currently working fine but there are some things missing:
the keyboard leds are not working (Caps Lock, Num
Lock)
Caps Lock for german umlauts are not implemented yet
Tabs are not yet supported
Btw, for keyboards other than german, the key table may need to be updated.
The card emulates the following codes from the host :
| Code | Hex | Function | Supported |
| ^H | 0x08 | Cursor left, no function @0,0, will go to prev line | Yes |
| ^I | 0x09 | TAB | No |
| ^K | 0x0B | Cursor Up, does nothing if @ first line | Yes |
| ^V | 0x16 | Cursor down with scroll | Yes |
| ^J | 0x0A | same as ^V | Yes |
| ^M | 0x0D | place cursor to row 0 | Yes |
| ^O | 0x0F | place cursor to row 0 and goto next line (with scroll) | Yes |
| 0x1Eh | 0x1E | Cursor home | Yes |
| ^Z | 0x1A | Clear Screen | Yes |
| ^L | 0x0C | Clear Screen (for CP/M) | Yes |
| ^G | 0x07 | Bell (Ignore) | Yes |
| ESC + | 0x2B | Clear Screen (Foreground only) | Yes |
| ESC ; | 0x3B | Clear Screen (Foreground only) | Yes |
| ESC * | 0x2A | Clear Screen to nulls | Yes |
| ESC : | 0x3A | Clear Screen (Clear unprotected page to nulls) | Yes |
| ESC . X | 0x2E | Set Cursor
attribute, "0":no cursor, "1":Blink, 2:non Blink block, 3:Blinking line, 4: steady line, 5:Blink Block, 6:fast Blink Block, 7:fast Blink line |
Yes |
| ESC ` X | 0x60 | same as ESC . | |
| ESC = YX | 0x3D | Set cursor position, X and Y with 20h offset, 20h is position zero | Yes |
| ESC E | 0x45 | Insert line at cursor pos, cursor will be on col 1 of inserted line | Yes |
| ESC R | 0x52 | Delete line at cursor pos, cursor at first pos of line | Yes |
| ESC T | 0x54 | Delete from cursor pos (including) to end of line | Yes |
| ESC t | 0x74 | same as ESC T | Yes |
| ESC Y | 0x59 | Delete from cursor pos (including) to end of screen | Yes |
| ESC y | 0x79 | same as ESC Y | Yes |
| ESC ) | 0x29 | Start Background (Dim) | Yes |
| ESC ( | 0x28 | Start Foreground (normal) | Yes |
| ESC 8 | 0x56 | Smooth scroll enable | No |
| ESC 9 | 0x38 | Smooth scroll disable | No |
| ESC W | 0x39 | Delete char | Yes |
| ESC Q | 0x51 | Insert Char | Yes |
| ESC ? | Read cursor address, Returns: line col CR | No | |
| ESC w | Read cursor address, Returns: page line col CR | No | |
| ESC / | Read cursor address, Returns: page line col CR or wnd line col CR (if screen split) | No | |
| ESC 0 | Clear all tab stops | No | |
| ESC 1 | Set tab stop | No | |
| ESC 2 | Clear tab stop | No | |
| ESC i | Tabulate cursor | No | |
| ^I | Tabulate cursor | No | |
| ESC I | Backtab | No | |
| ESC G attr | Assign character display attribute, starting with "0", Bit 0:Normal/Invisible, Bit1:Blink,Bit2:Reverse, Bit3:Underline | Yes | |
| x30 (0) Normal | Yes | ||
| x31 (1) Invisible | Yes | ||
| x32 (2) Blink | Yes | ||
| x34 (4) Reverse | Yes | ||
| x38 (8) Underline | Yes | ||
| ESC C x | Set Foreground Color, 3 Bit beginning with '0' | Yes | |
| ESC c x | Set Background Color, 3 Bit beginning with '0' | Yes | |
The keyboard codes are based on wordstar codes, at least wordstar and
turbo pascal works fine.
The ebc-interface uses port 80h-83h with the following functions:
80h: Read Status Port, Bit 7 ->
Character Available, Bit 6 = Ready for Output, Bit 2-0 only for Debug
Stuff
81h: Read KBD Input, Write Terminal
Output
82h: only used for Debugging Stuff
83h: only used for Debugging Stuff