Table of Contents
Construction Information
The most up-to-date board revision as of 5/29/2017 is 1.0-003. The Bill-Of-Materials below reflects a number of chip substitutions:
- Two of the 74LS244's are updated to 74ACT244 logic; one is unchanged
- Two of the 74LS374's are updated to 74ACT374 logic
- C1, 22uf on the schematic, is updated to 100uf or larger.
- Two 10uf Tantalum capacitors are substituted at C9 and C11.
The GAL chips are both ATF16V8BQL-15PU. The 15ns speed is important. Slower and faster GALs have led to unreliable operation. The -BQL suffix is the lowest power version.
Layout Indicating updates:
Construction Files
| Filename | Size | Updated |
|---|---|---|
| ECB-VGA3-BOM.png | 191kb | 26-May-2017 |
| ECB-VGA3-BOM.ods | 20kb | 26-May-2017 |
| ECB-VGA3-CUPL-JED.zip | 2.6kb | 07-May-2017 |
| ECB-VGA3-Gerber-mfg.zip | 0.6mb | 12-Apr-2017 |
Programming
The Programmers' Reference Manual is primarily for system programming at the BIOS level. Direct memory-mapped updating of display memory operates in a fashion identical to that of the IBM MDA/CGA/EGA/VGA adapters.
The schematic does not reflect the component substitutions specified in the BOM. Several components require update to faster versions.
| Filename | Size | Updated |
|---|---|---|
| VGA3-Programmers' Reference 1.1 | 333kb | 15-May-2017 |
| VGA3 Test Programs | 355kb | 24-Jul-2017 |
| VGA3 Schematic 1.0-003 | 493kb | 31-Jan-2015 |
| HD6445 Datasheet | 1023kb |
Testing
The test program ZIP file contains a tarball of the source, which includes a number of font files. The ZAP fonts are used under the GPL 3.0 license.
| Program | Description |
|---|---|
| v3mtst.com | Test of onboard memory. |
| v3tpat.com | 80×25 screen alignment pattern - jumpers HSYNC=neg, VSYNC=pos |
| v3tpat2.com | 80×30 screen alignment pattern - jumpers HSYNC=neg, VSYNC=neg |
| v3tpat3.com | 80×25 70hz screen alignment pattern - jumpers HSYNC=neg, VSYNC=pos. Escape to exit. |
| v3tpat4.com | 80×30 60hz screen alignment pattern - jumpers HSYNC=neg, VSYNC=neg. Escape to exit. |
| v3tpat5.com | 80×43 screen alignment pattern - jumpers HSYNC=neg, VSYNC=neg. Escape to exit. |
| vga3tty.com | Display keyboard scan codes through TTY interface. Reset to exit. |
| vga3kbd.com | Display keyboard scan codes through hardware interface. Reset to exit. |
Software configuration
Video output and keyboard input for the VGA3 board are supported in ROMWBW. It is included in the default build for the ECB-MK4 only.
To enable VGA3 board support in other ROMWBW builds, the following option should be enabled:
VGAENABLE .SET TRUE ; VGA: ENABLE VGA VIDEO/KBD DRIVER (VGA.ASM)
Screen formats supported are 80×25, 80×30 and 80×43, with 80×25 being the default. Display formats can be changed as follows:
VGASIZ .SET V80X30 ; VGA: DISPLAY FORMAT [V80X25|V80X30|V80X43]
