System RAM Usage
This table lists the usage assigned to specific registers and addresses for the RPD-95.
System | Byte | Contents |
|---|---|---|
| 000-003 | 0000-001F | Temporary System Usage |
| 004 | 0020-0023 | Temporary System Usage |
| 0024 | Current Program Code | |
| 0025 | Current Key Code | |
| 0026-0027 | Temporary System Usage | |
| 005 | 0028-0029 | User Flags 00-15 |
| 002A-002F | System Flags 16-63 | |
| 006 | 0030-0034 | System Flags 64-99 |
| 0035 | Temporary System Usage | |
| 0036 | AOS Stack Counter | |
| 0037 | Temporary System Usage | |
| 007 | 0038-003F | Numeric Display Register |
| 008-013 | 0040-006F | Temporary System Usage |
| 014 | 0070-0071 | Temporary System Usage |
| 0072-0073 | 1st address in currently running program or LEARN | |
| 0074-0075 | End address in currently running program or LEARN | |
| 0076-0077 | PC in currently running program or LEARN | |
| 015 | 0078-007F | Reserved for use by application cartridges |
| 016 | 2000-2007 | 1st AOS Operand |
| 017 | 2008-200F | 2nd AOS Operand |
| 018 | 2010-2017 | 3rd AOS Operand |
| 019 | 2018-201F | 4th AOS Operand |
| 020 | 2020-2027 | 5th AOS Operand |
| 021 | 2028-202F | 6th AOS Operand |
| 022 | 2030-2037 | 7th AOS Operand |
| 023 | 2038-203F | 8th AOS Operand |
| 024-026 | 2040-2057 | Temporary System Usage |
| 027 | 2058-2059 | If not expected values, memory will be cleared |
| 205A | User subroutine counter | |
| 205B | Last accepted key code | |
| 205C-205F | Temporary System Usage | |
| 028 | 2060-2067 | Operators for AOS operands |
| 2068-208F | Temporary System Usage | |
| 034 | 2090-2093 | Temporary System Usage |
| 2094 | Error Code | |
| 2095-2097 | Temporary System Usage | |
| 035-036 | 2098-20A7 | Temporary System Usage |
| 037 | 20A8-20AC | Temporary System Usage |
| 20AD-20AF | Name of file currently running | |
| 038 | 20B0-20B1 | Number of registers in partition |
| 20B2-20B3 | Address of 1st byte in register area | |
| 20B4-20B5 | Address of 1st byte in program area | |
| 20B6-20B7 | Program area PC | |
| 039 | 20B8-20BF | Characters for user definitions of F1-F5 |
| 040 | 20C0-20C6 | Characters for user definitions of F1-F5 |
| 20C7 | Flags and addresses for user definitions of F1-F5 | |
| 041-043 | 20C8-20DF | Flags and addresses for user definitions of F1-F5 |
| 044 | 20E0-20E4 | Flags and addresses for user definitions of F1-F5 |
| 20E5-20E7 | Temporary System Usage | |
| 045-047 | 20E8-20FF | Temporary System Usage |
| 048 | 2100-2106 | Temporary System Usage |
| 2107 | Result of SBA 21C | |
| 049-054 | 2108-2137 | Subroutine return stack |
| 055 | 2138 | Cursor position for alpha register |
| 2139 | Cursor position for system messages | |
| 213A | Printer device-number | |
| 213B | Printer width | |
| 213C-213F | Temporary System Usage | |
| 056-065 | 2140-218F | Alpha register |
| 066-067 | 2190-219F | System message |
| 068 | 21A0-21A5 | Temporary System Usage |
| 21A6 | Value for fix decimal | |
| 21A7 | Temporary System Usage | |
| 069 | 21A8-21AF | Temporary System Usage |
| 070 | 21B0-21B7 | Sum of y for statistics |
| 071 | 21B8-21BF | Sum of y² for statistics |
| 072 | 21C0-21C7 | N for statistics |
| 073 | 21C8-21CF | Sum of x for statistics |
| 074 | 21D0-21D7 | Sum of x² for statistics |
| 075 | 21D8-21DF | Sum of xy for statistics |
| 076 | 21E0-21E7 | Last x entered for statistics |
| 077 | 21E8-21EF | Last y entered for statistics |
| 078 | 21F0-21F7 | Frequency for statistics |
| 079 | 21F8-21FF | t-register |
| 080-101 | 2200-22AF | Temporary System Usage |
| 102 | 22B0-22B7 | Flags and address for last BREAK command |
| 103 | 22B8-22BA | Flags and address for last BREAK command |
| 22BB-22BF | Temporary System Usage | |
| 104-108 | 22C0-22E7 | Temporary System Usage |
| 109-110 | 22E8-22F7 | Printer PAB |
| 111 | 22F8-22FF | Temporary System Usage |
| 112-113 | 2300-230F | Random number seed |
| 114-139 | 2310-23DF | Temporary System Usage |
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