The AWA RT85A is a later variant of the RT85, and comes in two
Unfortunately the RT85 and RT85A models are all marked as "RT85" on the name plate, so it is neccesary to open the radio for identification.
The RT85C and Midland 70-530A are similar radios however the
following notes may not apply.
All versions are basically the same radio with different microprocessor controllers.
The original RT85 has a mask programmed microprocessor mounted on the main transmitter PCB. A small detachable daughter board contains a EPROM and a shift register chip and could be removed for programming in a proprietary Midland Programmers model 70-1000 and 70-1000C.
The RT85A version replaces the onboard microprocessor on the main PCB with a new micro mounted on a larger daughter board that plugs into the same connectors previously used for the EPROM board on the original RT85.
RT85A version 1:
The first variant of the RT85A processor board uses a 40-pin mask
Motorola 146805G2 microprocessor, with a 2k byte 2716 type EPROM and a
shift register chip. In this version the EPROM only stores
and configuration data, and a few "library" functions. The main
code is stored internally in the microprocessor at the time of
is not readily accessible and cannot be changed.
The "Library" functions are used to extend the functionality of the radio for specific applications that were not thought of at design time. They also allow some errors in the original program code to be overcome without having manufacture the very expensive masked ROM in the microprocessor. These functions are loaded in from the EPROM and executed at key points in the main intenally masked ROM program whenever certain option bits at EPROM addresses $03F6 & $03F7 are set.
This version of the radio can be identified by the small PCB mounted face up near the VCOs, and contains a 2716 EPROM, a 40-pin Motorola microprocessor chip, and a small logic chip.
RT85 version 2:
A later variant of the RT85A uses a 64-pin Hitachi HD6305Y2P
microprocessor, a 8k 2764 EPROM, and has no shift register chip.
EPROM in this model stores both the main program, as well as frequency
and configuration data, making the radio a lot more flexible in special
Channel and Configuration Data:(Note '$' signifies hexadecimal values)
The frequency (channel) data and the configuration (personality) data follow a nearly identical format in both the 2716 and 2764 EPROMs, except that this data is offset by an address of $1000 (hex 1000). The 2764 has the main program for the CPU stored in the EPROM below $1000. Whereas version 1 with the 2716 EPROM has "library" functions interspersed with this data, version 2 with the 2764 EPROM does not. Version 2 does not need to use "Library" functions since the main program can easily be modified in the EPROM.
The following table lists the function of each bit in the Personality Data:
* Personality Data - AWA RT85A (RDNS versions)
* For MC6805 + 2716 EPROM version.
* EPROM $03F0 - $03FC
* Addresses for HD6305 + 2764 EPROM version are offset by $1000 and are shown in brackets ( $nnnn ).
* NOTE: anything marked with '??' is questionable.
* Further advice requested. Send a message to vk3byy via the Contact form at nerg.asn.au
^^^^-^^^^--MAXCHAN FF ; Highest Channel number (01 to 99)
^^^^--TXLIMIT 0F ; TX Timeout value
; 0=continuous, time(secs) = n*15
^-------DSPBLNK 10 ; Enable Display Blanking after 20 seconds
^--------TXIBUSY 20 ; Enable Transmit Inhibit on BUSY
^---------TXIOPEN 40 ; Enable Transmit Inhibit on OPEN
^----------DPWRENB 80 ; Enable Hi/Lo output power link
; (Depower link) on back of control head
^--SCANENB 01 ; Enable Scanning
^---SCANTSQ 02 ; Enable Scan Stop with CTCSS
^----SCANDEL 04 ; Enable Chan DOWN key Deletes Scan Channel
^-----SCANHUR 08 ; Enable Hangup up Resets Scan ????
^-------SCANPROG 10 ; Enable Self-Programming
^^^--------SCANHLD E0 ; Scan hold time ( 0 - 7 seconds)
^--OPENHU 01 ; Enable Silent switch
^---TSQENB 02 ; Enable Tone Squelch (CTCSS on receive)
^----SELCENB 04 ; Enable SELCALL
^-----STATENB 08 ; Enable SELCALL Status call
^-------ANILEAD 10 ; Enable SELCALL
^--------ANITRAIL 20 ; Enable SELCALL Trailing ANI
^---------ANIBEEP 40 ; Enable Send ANI with beep
^----------CAR2CAR 80 ; Enable SELCALL Car to Car call
^^^^--TIMER44 ; ANI SELCALL lead-in time (1=short, 15,0=long)
^-------BSYDLY5 ; Enable Busy LED 5
^--------SILSWEN ; Enable Silent switch ??
^---------SNDIBUSY ; Enable SEND Inhibit on BUSY
^----------SNDIOPEN ; Enable SEND Inhibit on OPEN
^--VOTENB ; Enable Voting (if option fitted)
^---xxxx ; an option with timers, SELCALL, and beeps ??
^----SCANLED ; Enable SCAN LED as Power Indicator
^-----OPENLED ; Enable OPEN LED
^^^^-------TONEPER ; SELCALL tone period (0,F=slow,
^--SCTXDEC ; Bypass TX code initialisation of SELCALL
^---xxxxxx ; unused (another CTCSS option in 2764 ver. ??)
^----F320 ; Enable Lib 320 ?? (unused in 2764)
^-----F340 ; Enable Lib 340 ?? (unused in 2764)
^-------xxxxxx ; Enable Lib 360 ?? (unused in 2764)
^--------xxxxxx ; Enable Lib 380 ?? (unused in 2764)
^---------xxxxxx ; Enable Lib 3A0 ?? (unused in 2764)
^----------unused ; unused
^--unused ; Enable Lib 680 ?? (unused in 2764)
^---unused ; Enable Lib 6C0 ?? (unused in 2764)
^----unused ; Enable Lib 6E0 ?? (unused in 2764)
^-----ALARMRST ; Enable ALERT reset enable via Depower/Hangup link
^-------unused ; Enable Lib 720
(unused in 2764)
^--------xxxx ; Enable Depower link as DOWN key in user scan ??
^---------unused ; unused
^----------unused ; unused
* SELCALL ID - 5 digits, RX and TX digits combined into one byte.
* Transmit digits in highest 4 bits, Receive digits in lower 4 bits.
* Digits adjacent should not be the same (eg 24310 is OK, but 24430 is
tttt rrrr ;1st digits TX & RX
tttt rrrr ;2nd digits
tttt rrrr ;3rd digits
tttt rrrr ;4th digits
tttt rrrr ;5th digits
--- end ---
Enable scanning by setting bits in
the personality data:
Turn on the scan option by setting bit 0 ($01) in byte $03F2. Also set bit 2 ($04) if you want the "DOWN" button to skip over (delete) certain busy channels . Up to 4 channels can be skipped (useful where some repeaters suffer occasionally from LIPD interference for instance). I haven't figured out Self programming (user programming) options yet.
Enter the number of each channel to scan into a list starting at address $0000 ($1000 for ver 2), with each entry spaced 4 bytes apart. The list must end with a value $FF. Note that the scan channel data runs contiguously through the EPROM address space, unlike the channel data has a break between channel 9 and 10, between 19 and 20, etc.. Channel numbers are represented binary coded decimal, or in other words, as two digits, the tens digit stored in the 4 high bits, and the ones in the 4 low bits (as displayed on the front panel, so channel 13 is entered as hexadecimal $13).
Channels can be in any order, and can include channel 0.
can occur more than once if you want to check them more often than the
To scan channels 1,2,15,4,10,20,30,40,51,52,53,54,55,56,57,58,59 we enter the following data at the addresses indicated: (note there is no gap between addresses $0024 and $0030 - all are used).
$0000 01 ;first scan channel = ch 1
$0004 02 ;second scan channel= ch 2
$0008 15 ; third scan channel = ch 15
$000C 04 ; forth scan channel = ch 4
$0010 10 ;fifth = ch 10
$0014 20 ; etc...
$0044 FF ;end of scan list
$004C FF, etc....
--- end ---