VMC: ISDN Blaster Z2
Connection: Zorro II


The ISDN-Blaster is an ISDN ataptor on a full length Zorro II card.

ISDN s0 BRI (Basic Rate Inferface)
Error check: HDLC
Rate: 2 * 64,000 bits per second
Serial FIFO: 2 * 32 byte transmit / to 32 byte of receipt FIFO
Expansion port for additional expansion modules (note: this is a buggy feature, see below) Ultra high speed to max. 2 times 64,000 bits per second (128 KBit)

Intelligent Features

Supports ZModem optimised transmissions for up to 20% more data through-put
Supports Internet of T-Online access
Up to 10 adjustable MSN numbers per device
ISDN Setclock, sets the Amiga clock on the ATOM exact time of day transferred in the ISDN D-Channel. Automatic recognition of the B-Channel log of the caller. B Channel supports the following protocols:
X75, T.70 NL, T.90, V.110, V.120, PPP

D Channel supports the following protocols:
German 1TR6 and European EDSS1

The following is courtesy of Michael Boehmer.

Known bugs

On the vmc isdn blaster, a couple of bugs is known to be present:

o The card configures with a chained config request, so the Amiga thinks the card in the slot behind the blaster is located on the same PIC. Urgency: Mostly harmless, correctable.
o The card stores only the upper three bits of the base address, assuming that it will get a place in the address space between 0xe80000 and 0xef0000. Urgency: Dangerous, not correctable.
o The address decoding does not differenciate between the ISDN chipset and the expansion socket. This bug is only noticable when an expansion module is present. Urgency: Dangerous, correctable


The isdn blaster requests 64kB address space in the I/O region (in Amigas, normally between 0xe80000 and 0xefffff). In the lower 32kB (i.e. A15 is low) the ISDN chips are located (the chipselects are generated out of A8 and A9), in the upper 32kB (i.e. A15 is high) is address space for expansion modules (the hyperCOM 3i uses A8 and A9 for internal chipselects in the UART).

Unfortunately, the PALCEs on the blaster have no connection to the A15 line, so the ISDN chips are mirrored into the expansion space, which leads to very strange effects (data bus contentions, driver misbehaviour). The hyperCOM 3i module seems to handle the A15 line correctly.

The hardware patch attaches the missing A15 line to one of the PALCEs, the new JEDEC files are necessary for the new address decoding. Unfortunately, someone had set the copy protection bit in both PALCEs, so a completely new design had to be done. This means that you have to desolder both PALCEs.

The JEDEC files also correct the chained config request bug. Moreover, the vmc isdn blaster card now has a new serial number (0x4d42 instead of 0x0000), so the driver can distinguish

For instructions on patching the card, please see Michael Boehmers Page

Contributions to this page by:
Michael Böhmer, Sebastian Kinner

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