VCF XT-IDE Rev 4
This is the fourth revision of the XT-IDE card produced by the Vintage Computer Forums (VCF), not the first nor second nor third revisions.
Printed on the card is "XT-IDE rev 04".
Before reading further, read the web page at here, to gain information on the basics of the XT-IDE.
Early history of Rev 4
AUG2017: Printed Circuit Board (PCB) developed by glitch.
OCT2017: glitch selling kits, and assembled units, on eBay. (Beware of inferior versions [e.g. no bypass capacitor for each IC].)
• The development thread is here.
Significant changes from Rev 3
Essentially, the Rev 4 card is a Rev 3 card with the following enhancements:
• "Delay chains for improved ATA drive compatibility"
• "Jumper pads for easier installation of Slot 8 Support (GW-S8S-2) module"
Switch/jumper settings are the same.
Hi-Speed mode versus Compatibility mode
• Just like with the XT-IDE Rev 3 card, it is expected (only for performance reasons) that the Rev 4 card be jumpered for hi-speed mode, and using a 2.x.x version of the XTIDE Universal BIOS (per option #1 in the table below).
• Compatiblity mode changes the IDE interface (specifically, its register map) to how it is on an XT-IDE Rev 1 card. You will need to jumper your Rev 4 card for this mode if you choose to use a 1.x.x version of the XTIDE Universal BIOS, or you have an Olivetti M24 or AT&T PC6300.
• The three options for the Rev 4 card are show in the following table:
Some technical information on this subject is at here.
A diagram for the IDE functionality is at here
A diagram for the ROM functionality is at here
On the card, if you change the base I/O address of the IDE interface from the default of 300 (hex), then you will need to reflect that change within the XTIDE Universal BIOS within the EEPROM (so that the BIOS knows which I/O addresses to use).
For example, the applicable area of the configuration/flashing tool for version 1.1.5 of the XTIDE Universal BIOS is shown at here.