diff --git a/src/device/isapnp.c b/src/device/isapnp.c
index 0139eeb23..470147953 100644
--- a/src/device/isapnp.c
+++ b/src/device/isapnp.c
@@ -137,6 +137,8 @@ isapnp_device_config_changed(isapnp_card_t *card, isapnp_device_t *ld)
         card->config.mem[i].size = (ld->regs[reg_base + 3] << 16) | (ld->regs[reg_base + 4] << 8);
         if (ld->regs[reg_base + 2] & 0x01) /* upper limit */
             card->config.mem[i].size -= card->config.mem[i].base;
+        else
+            card->config.mem[i].size = (card->config.mem[i].size | 0xff) ^ 0xffffffff;
     }
     for (uint8_t i = 0; i < 4; i++) {
         reg_base                   = (i == 0) ? 0x76 : (0x80 + (16 * i));
@@ -789,10 +791,25 @@ isapnp_update_card_rom(void *priv, uint8_t *rom, uint16_t rom_size)
                             break;
                         }
 
-                        isapnp_log("ISAPnP: >>%s Memory range %d with %d bytes at %06X-%06X, align %d",
-                                   in_df ? ">" : "", mem_range,
-                                   *((uint16_t *) &card->rom[i + 10]) << 8, *((uint16_t *) &card->rom[i + 4]) << 8, ((card->rom[i + 3] & 0x4) ? 0 : (*((uint16_t *) &card->rom[i + 4]) << 8)) + (*((uint16_t *) &card->rom[i + 6]) << 8),
-                                   (*((uint16_t *) &card->rom[i + 8]) + 1) << 16);
+                        isapnp_log("ISAPnP: >>%s Memory range %d with %d bytes at %06X-%06X to %06X-%06X, align %d",
+                                   /* %s   */ in_df ? ">" : "",
+                                   /* %d   */ mem_range,
+                                   /* %d   */ *((uint16_t *) &card->rom[i + 8]),
+                                   /* %06X */ *((uint16_t *) &card->rom[i + 4]) << 8,
+                                   /* %06X */ ((card->rom[i + 3] & 0x4) ?
+                                              /* High address. */
+                                              (*((uint16_t *) &card->rom[i + 10]) << 8) :
+                                              /* Range. */
+                                              (*((uint16_t *) &card->rom[i + 4]) << 8)) +
+                                              (*((uint16_t *) &card->rom[i + 10]) << 8),
+                                   /* %06X */ *((uint16_t *) &card->rom[i + 6]) << 8,
+                                   /* %06X */ ((card->rom[i + 3] & 0x4) ?
+                                              /* High address. */
+                                              (*((uint16_t *) &card->rom[i + 10]) << 8) :
+                                              /* Range. */
+                                              (*((uint16_t *) &card->rom[i + 6]) << 8)) +
+                                              (*((uint16_t *) &card->rom[i + 10]) << 8),
+                                   /* %d   */ *((uint16_t *) &card->rom[i + 8]));
                         res = 1 << mem_range;
                         mem_range++;
                     } else {
@@ -806,9 +823,25 @@ isapnp_update_card_rom(void *priv, uint8_t *rom, uint16_t rom_size)
                             break;
                         }
 
-                        isapnp_log("ISAPnP: >>%s 32-bit memory range %d with %d bytes at %08X-%08X, align %d", in_df ? ">" : "", mem_range_32,
-                                   *((uint32_t *) &card->rom[i + 16]) << 8, *((uint32_t *) &card->rom[i + 4]) << 8, ((card->rom[i + 3] & 0x4) ? 0 : (*((uint32_t *) &card->rom[i + 4]) << 8)) + (*((uint32_t *) &card->rom[i + 8]) << 8),
-                                   *((uint32_t *) &card->rom[i + 12]));
+                        isapnp_log("ISAPnP: >>%s 32-bit memory range %d with %d bytes at %08X-%08X, align %d",
+                                   /* %s   */ in_df ? ">" : "",
+                                   /* %d   */ mem_range_32,
+                                   /* %d   */ *((uint32_t *) &card->rom[i + 12]),
+                                   /* %08X */ *((uint32_t *) &card->rom[i + 4]),
+                                   /* %08X */ ((card->rom[i + 3] & 0x4) ?
+                                              /* High address. */
+                                              *((uint32_t *) &card->rom[i + 16]) :
+                                              /* Range. */
+                                              *((uint32_t *) &card->rom[i + 4])) +
+                                              *((uint32_t *) &card->rom[i + 16]),
+                                   /* %08X */ *((uint32_t *) &card->rom[i + 8]),
+                                   /* %08X */ ((card->rom[i + 3] & 0x4) ?
+                                              /* High address. */
+                                              *((uint32_t *) &card->rom[i + 16]) :
+                                              /* Range. */
+                                              *((uint32_t *) &card->rom[i + 8])) +
+                                              *((uint32_t *) &card->rom[i + 16]),
+                                   /* %d   */ *((uint32_t *) &card->rom[i + 12]));
                         res = 1 << (4 + mem_range_32);
                         mem_range_32++;
                     }
diff --git a/src/scsi/scsi_aha154x.c b/src/scsi/scsi_aha154x.c
index e3f38c4e5..58779e7ac 100644
--- a/src/scsi/scsi_aha154x.c
+++ b/src/scsi/scsi_aha154x.c
@@ -678,6 +678,7 @@ aha_pnp_config_changed(uint8_t ld, isapnp_device_config_t *config, void *priv)
                 aha_eeprom_save(dev);
 
                 dev->rom_addr = config->mem[0].base;
+                aha_log("Base = %08X, Size = %08X\n", config->mem[0].base, config->mem[0].size);
                 if (dev->rom_addr) {
                     mem_mapping_enable(&dev->bios.mapping);
                     aha_log("SCSI BIOS set to: %08X-%08X\n", dev->rom_addr, dev->rom_addr + config->mem[0].size - 1);
@@ -869,13 +870,12 @@ aha_setmcode(x54x_t *dev)
     }
     aha1542cp_pnp_rom = (uint8_t *) malloc(dev->pnp_len + 7);
     fseek(fp, dev->pnp_offset, SEEK_SET);
-    (void) !fread(aha1542cp_pnp_rom, dev->pnp_len, 1, fp);
+    (void) !fread(aha1542cp_pnp_rom, 4, 1, fp);
     memset(&(aha1542cp_pnp_rom[4]), 0x00, 5);
     fseek(fp, dev->pnp_offset + 4, SEEK_SET);
     (void) !fread(&(aha1542cp_pnp_rom[9]), dev->pnp_len - 4, 1, fp);
-    /* Even the real AHA-1542CP microcode seem to be flipping bit
-       4 to not erroneously indicate there is a range length. */
-    aha1542cp_pnp_rom[0x87] |= 0x04;
+    /* Patch determined from Dizzy's AHA-1542CP PNP ROM dump. */
+    aha1542cp_pnp_rom[0x26] = 0x03;
     /* Insert the terminator and the checksum byte that will later
        be filled in by the isapnp code. */
     aha1542cp_pnp_rom[dev->pnp_len + 5] = 0x79;