SCM, v1.1, Configurations

The Small Computer Monitor supports a range of hardware and options. These are determined at compile time and are identified by a configuration code. The current configurations are listed below.

Only a few of these have been ported from SCM v1.0 to SCM v1.1

Config.DescriptionROMRAM
00Complete custom build
C1Z80sc, standard ROM
SCM, BASIC, CP/M loader
Maintained by SCCousins
1 bank
of 32k
32k or
64k paged
F1Z50Bus, standard ROM
SCM, BASIC, CP/M loader
Maintained by SCCousins
1 bank
of 32k
32k or
64k paged
L1LiNC80 SBC1, standard ROM
SCM, BASIC, CP/M loader
Maintained by SCCousins
and Jon Langseth
2 banks
of 16k
48k or
64k paged
R1RC2014, official image 9
SCM only
Maintained by SCCousins
1 bank
of 8k
32k
no paging
R2RC2014
SCM and BASIC
Maintained by SCCousins
1 bank
of 16k
48k
no paging
R3RC2014
SCM, BASIC, CP/M loader
Maintained by SCCousins
1 bank
of 32k
32k or
64k paged
R4RC2014, official image 88
SCM, BASIC, CP/M loader
Maintained by SCCousins
1 bank
of 16k
32k or
64k paged
S1SC101, standard ROM
SCM, BASIC, CP/M loader
Maintained by SCCousins
1 bank
of 8k
32k or
64k paged
S2SC114, standard ROM
SCM, BASIC, CP/M loader
Maintained by SCCousins
1 bank
of 32k
32k or
64k paged
S3SC108, standard ROM
SCM, BASIC, CP/M loader
Maintained by SCCousins
1 bank
of 32k
32k or
64k paged
S4SC111, Z180 CPU
SCM, BASIC, CP/M loader
Maintained by SCCousins
1 bank
of 32k
32k or
64k paged
S5SC111+SC119, Z180 system
SCM, BASIC, CP/M loader
Maintained by SCCousins
512k
Z180 MMU
512k
Z180 MMU
S6SC126, Z180 Motherboard
SCM, BASIC, CP/M loader
Maintained by SCCousins
512k
Z180 MMU
512k
Z180 MMU
T1Tom’s SBC revision C
SCM, BASIC, CP/M loader
Maintained by SCCousins
1 bank
of 16k
48k or
84k paged
Z1Z280RC by Bill Shen
Maintained by Bill Shen
Z?Z80SBC64 by Bill Shen
Maintained by Bill Shen

Notes

S4
This configuration is designed as a stepping stone from a working Z80 based RC2014 to a Z180 processor. Simply replace the Z80 CPU with a Z180 CPU and install this version of SCM. All I/O is provided by the existing external hardware (not the Z180) and any required memory management is also provided by existing external hardware.

S5
This configuration is used when a complete Z180 design is required. Z180 internal peripherals, such as serial, are used instead of external ones.

Supported Hardware

The following hardware is specifically supported, and used, by SCM. Other hardware may also exist in the system, but SCM does not provide support or use it. However, software loaded and run from SCM might make use of such hardware.

Config.Supported hardware
F1Z80 CPU (eg. Z84C00xx)
SIO #1 at 0x80 (eg. Z84C42xx)
CTC #1 at 0x88 (eg. Z84C30xx)
Bit-bang serial port
Digital I/O at 0x52
Compact Flash at 0x10 for loading CP/M
L1Z80 CPU (eg. Z84C00xx)
SIO at 0x00 (eg. Z84C42xx)
CTC at 0x08 (eg. Z84C30xx)
Digital I/O at 0x30
R1 & R2Z80 CPU (eg. Z84C00xx)
ACIA #1 at 0x80 (eg. 68B50)
ACIA #2 at 0x40 (eg. 68B50)
SIO #1 at 0x80 (eg. Z84C42xx)
Digital I/O at 0x00
R3 & R4Z80 CPU (eg. Z84C00xx)
ACIA #1 at 0x80 (eg. 68B50)
ACIA #2 at 0x40 (eg. 68B50)
SIO #1 at 0x80 (eg. Z84C42xx)
Digital I/O at 0x00
Compact Flash at 0x10 for loading CP/M
S2Z80 CPU (eg. Z84C00xx)
ACIA #1 at 0x80 (eg. 68B50)
ACIA #2 at 0x40 (eg. 68B50)
SIO #1 at 0x80 (eg. Z84C42xx)
Bit-bang serial port (as SC114)
Digital I/O at 0x00
Compact Flash at 0x10 for loading CP/M
S3Z80 CPU (eg. Z84C00xx)
ACIA #1 at 0x80 (eg. 68B50)
ACIA #2 at 0x40 (eg. 68B50)
SIO #1 at 0x80 (eg. Z84C42xx)
CTC #1 at 0x88 (eg. Z84C30xx)
Digital I/O at 0x00
Compact Flash at 0x10 for loading CP/M
S4Z180 CPU (eg. Z8S180xx)
ACIA #1 at 0x80 (eg. 68B50)
ACIA #2 at 0x40 (eg. 68B50)
SIO #1 at 0x80 (eg. Z84C42xx)
CTC #1 at 0x88 (eg. Z84C30xx)
Digital I/O at 0x00
Compact Flash at 0x10 for loading CP/M
S5Z180 CPU (eg. Z8S180xx)
Z180’s asynchronous serial ports
Z180’s internal timer (for idle events)
Digital I/O at 0x00
Compact Flash at 0x10 for loading CP/M
S6Z180 CPU (eg. Z8S180xx)
Z180’s asynchronous serial ports
Z180’s internal timer (for idle events)
Digital I/O at 0x00
Compact Flash at 0x10 for loading CP/M
Status / self-test LEDs at 0x0D

Hardware Identification Codes

These are hardware identifiers used within SCM and returned as part of the SCM version details.

Config.DescriptionIDNameHardware
0#Custom0<custom>
C#Z80sc13Z80scSC121
F#Z50Bus14Z50BusSC118
L#LiNC805LiNC80SBC1
R#RC20143RC2014Z80
S1SC_S14SC101SC101
S2SC_S28SC114SC114
S3SC_S310SC3SC108
S4SC_S411Z180SC111
S5SC_S512Z180_RCSC111+119
S6SC_S612SC126SC126
T1TomsSBC6TomsSBCSBC vC
W#Simulated1Simulated
Z1Z280RC7Z280RCZ280RC
Z2Z80SBC649Z80SBC64Z80SBC64
SCDevKit012SCDevKit01

Hardware Flags Summary

Hardware identified by SCM is indicated by the flags described below. These flags are returned as part of the SCM version details.

SCM
Config.
bit
7
bit
6
bit
5
bit
4
bit
3
bit
2
bit
1
bit
0
Z80sc
C#
Z180
serial
CTC
0x8C
SIO
0x84
CTC
0x88
Bit-
bang
ACIA
0x40
SIO
0x80
ACIA
0x80
Z50Bus
F#
n/aCTC
0x8C
SIO
0x84
CTC
0x88
Bit-
bang
n/aSIO
0x80
n/a
LiNC80
L#
n/an/a n/a n/a n/a n/a n/a SIO 1
0x00
RC2014
R#
Z180
serial
CTC
0x8C
SIO
0x84
CTC
0x88
Bit-
bang
ACIA
0x40
SIO
0x80
ACIA
0x80
RC2014
S#
Z180
serial
CTC
0x8C
SIO
0x84
CTC
0x88
Bit-
band
ACIA
0x40
SIO
0x80
ACIA
0x80
TomsSBC
T1
n/a n/a n/an/an/an/an/aSIO 1
0x00

Hardware Flags for RC2014 Systems

Hardware flags for other configurations of SCM may indicate different hardware.

Flag bitHardware for SCM configurations R# and S#
Bit 0ACIA #1 at 0x80
Bit 1SIO #1 at 0x80
Bit 2ACIA #2 at 0x40
Bit 3Bit-bang serial, or
SIO #1 in RC2014 addressing compatibility mode
Bit 4CTC #1 at 0x88
Bit 5SIO #2 at 0x84
Bit 6CTC #2 at 0x8C
Bit 7Z180’s internal serial ports

Hardware flag for each configuration are detailed below.

SCM
Config.
bit
7
bit
6
bit
5
bit
4
bit
3
bit
2
bit
1
bit
0
RC2014
R1 to R4
00000ACIA
0x40
SIO
0x80
ACIA
0x80
RC2014
S2
0000Bit-
bang
ACIA
0x40
SIO
0x80
ACIA
0x80
RC2014
S3
000CTC
0x88
SIO 1
mode
ACIA
0x40
SIO
0x80
ACIA
0x80
RC2014
S4
000CTC
0x88
SIO 1
mode
ACIA
0x40
SIO
0x80
ACIA
0x80
RC2014
S5
Z180
serial
0000000
RC80
S6
Z180
serial
0000000

Homebrew 8-bit retro computing