EMMA 02

General Information

The V-ELF is a combination of the COSMAC VIP and COSMAC ELF systems. With the flip of a switch, the V-ELF behaves like either the COSMAC ELF or VIP (using the JVIP ROM)

ELF mode:

• 32K of RAM is mapped to 0 - @7FFF
• 32K of ROM is mapped to @8000 - @FFFF

The system doesn't do much on it's own and requires you to enter a program via the input switches or execute what ever program has been put/left in RAM from the VIP Monitor or VELF Bios ROM.

VELF MENU:

COSMAC ELF says Hello (v3.1)
[D] Dump, [E] Enter, [R] Run ?

Here, you may talk to your ELF via your terminal program.

• D-Dumps Memory 1 page at a time, Enter an address, dumps next page, to quit.
• E-Enters Data into the RAM, Enter an address, Enter Data, to next byte, to quit.
• R-Runs at what ever address you select, Enter an address.
• Or pressing the "IN" button will cause the VElf to execute the VIP monitor or Load a program into RAM from ROM.

Pressing the IN button at any time (checked during the RS232 RXCHAR routine) will cause execution to go to the VIP monitor or preload a program from ROM into RAM. If the dip switches are all off, then the VIP monitor program is loaded. Otherwise, the program number selected by the dip switches is loaded into RAM from the BIOS ROM. See "pgmtable" for a list of loadable programs contained within this ROM.

pgmtable:
1 = Starship (as listed in part 4 of the COSMAC ELF - Popular Electronics Jully 1977 issue)
2 = SumFun (as listed in the VIP Games Manual)
3 = PinBall (as listed in the VIP Games Manual)
4 - FF are not defined in this version.

If the IN button is pressed with dip switches all off, then VIP Monitor is started. The VIP Monitor requires you to hold down the "C" key to enter the Monitor program. Hold "C" while pressing IN button. If you do not hold down the C key, execution of code at 0000 will occur. Once the monitor program is entered, it tests to see how many pages of RAM are available, starting at 4K it then clears the last 80 bytes of ram in the last page of ram (hex F00 in the VElf) for a Video Display. After you release the "C" button, you must enter a 4 digit starting address: XXXX

Then select what to do as follows:
"0" to begin entering data into RAM, keep entering 2 digit hex values for consecutive RAM addresses
"A" to view memory, any key displays the next byte
"B" to read data from TAPE Drive (via EF2 line), enter the number of pages to READ
"F" to write data to TAPE Drive (via Q line), enter the number of pages to WRITE

VIP mode:

• 32K of RAM is mapped out until A15 goes high (a Long Branch to @8200 does this)
• 32K of ROM is mapped to both 0 - @7FFF and @8000 - @FFFF

Execution goes directly to the VElf Bios at @8200 where the VElf starts talking through RS232 (Q for TXD, EF2 for RXD) by sending it's Menu at 9600,N,8,1.

Before starting execution by switching the RUN switch (pressing F12 in Emma 02) press one of the following options.

• Press and hold C until the Beep and the JVIP will run the standard VIP monitor
• Press and hold D until the Beep and the JVIP will run Josh Bensadon's Serial monitor
• Press and hold E until the Beep and the JVIP will copy CHIP8 from rom to ram and then halts for reset.
• Press and hold F until the Beep and the JVIP will copy CHIP8 and PinBall from rom to ram and then halts for reset.
• Press and hold A until the Beep and the JVIP will copy CHIP8 and Animal Race from rom to ram and then halts for reset.
• Press and hold 1 until the beep and the JVIP will copy the COSMAC Starship image to ram and then haults for reset.
• Press and hold 2 until the beep and the JVIP will copy CHIP8 and Lunar Lander from rom to ram and then halts for reset.
• With nothing held down, the JVIP will being executing code at 0

Technical specifications

Clock: 3.5795 MHz
Memory:
      32 KB RAM
      32 KB ROM
Video: CDP1861
Sound: One fixed frequency tone
Keyboard: CD4515 (for hexadecimal keypad)

Screen shot

VELF startup menu on a video terminal.